Travel advice: US hotel charges; using an iPad abroad; visiting Bornholm Gill Charlton replies An increasing number of hotels, notably in the US, request a credit card on check-in as security against charges. The card is used to "pre-authorise" a sum - effectively ring-fencing it so it cannot be spent elsewhere. When the customer checks out of the hotel, the authorised funds are released. However, if customers use a debit card there is no pre-authorisation facility, so hotels may put through a sum to cover possible extras or ask for a cash payment. Any unused credit is refunded to the card on checkout, but this can take up to 10 business days to reach your account. The Venetian says that it requires a deposit of $100 (£62) a room per night as security against extras such as food, drink and minibar charges. It debits an extra $150 (£94) per room per night if customers want to charge dining, spa services and entertainment to their room. Unfortunately, the hotel says it can no longer find Nicholas's reservation as it came through an agent. But if he handed over a credit card it should not have been debited, only subjected to the pre-authorisation procedure. I suspect that the desk clerk made a mistake and treated it as a debit card. I would advise ensuring you have a high enough credit limit to cover pre-authorisation costs. If a hotel does charge the card and leave you out of pocket when releasing the sum, contact the hotel immediately to sort it out. I would also take a second credit card - or use a debit card or travel money card - for spending and ATM withdrawals. In touch on the road Alan Cowley, Ashford, Kent, writes We are spending five months travelling through India, south-east Asia and Australia and would like to be in touch regularly with our families. What is the best and most economical way to use iPhone and iPad to do this? Gill Charlton replies I found my iPhone so expensive for sending and receiving emails abroad that I have now traded it in for a Blackberry, which is far cheaper and downloads emails much faster. I also carry an iPad, which is a great tool for keeping in touch from these countries as many hotels - even cheap ones - now have free Wi-Fi internet access. If not, there will be a man in a booth down the street selling Wi-Fi access. As well as sending your family and friends emails and photographs, you can make video calls using your iPhone or iPad if you subscribe to the Skype service (skype.com). Calls are free if relations with internet access also sign up for the service. There's a small charge for making Skype calls to landlines. Flight cancellations Eric Jones, London, writes My wife and I were booked on a return flight from London to Boston with American Airlines (AA) in November. I had to cancel the flights because of illness. My insurer says the email cancellation invoice sent by AA is not sufficient proof that we did not use the flights. Over the last four months I have sent recorded delivery letters and emails to AA in both Britain and the United States asking for a printed "letter of cancellation." I have also spoken to AA call centres as far afield as Fiji. But no letter has yet appeared. What else can I do? Gill Charlton replies It can be frustrating trying to obtain a letter of cancellation from an airline. Some now charge for the service. The best way to submit a request is to use the online customer-services form, which can usually be found under the "information" or "help" sections of the airline's website. AA in Britain apologises for the long delay in providing the letter, which it puts down to a move of office. It has now sent out the requested letter and is offering you 5,000 air miles in compensation for the inconvenience. The airline says that it aims for a five-day turnaround when requests are input online, as writing in is no longer the best way to proceed. Go to "Customer Relations" and click on "Delay/Cancellation Verification" for the request form. The best way to Bornholm Nick Sherman, Borehamwood, Herts, writes We are considering a summer holiday on the Danish island of Bornholm. We are a family of four (children of 14 and 10) and enjoy the outdoor life. It is difficult to access information as some websites are only in Danish. For a start, I'm confused as to the best way of getting there. Should we drive or can we use public transport? Gill Charlton replies If in your own car, take the ferry from Harwich to Esbjerg and continue via Copenhagen and Sweden to Bornholm. To book a ferry, visit bornholmexpress.dk. If you fly, note that Bornholm Express runs a three-hour coach/ship transfer from Copenhagen to Bornholm. One of the best ways to explore Bornholm's 65-mile coastal road is by bicycle. Contact Bornholms Cykeludlejning in Rønne (0045 5695 1359) to reserve bicycles. The landscape is remarkably varied and warm Baltic currents make the island's climate mild enough to support figs and mulberries. But I would take wetsuits if you want to swim off the white-sand beaches (notably Dueodde in the south). The hilly interior has impressive waterfalls and walking trails and supports an artists' colony. On most summer weekends there are craft markets in bigger towns. A good source of information on accommodation and transport is Destination Bornholm's website: bornholm.info/en. Contact Gill Queries may be sent by email to askgill@telegraph.co.uk. Please provide your full address, daytime telephone number and any booking reference. Readers with complicated complaints may be asked for full documentation. We regret that we are no longer able to answer postal inquiries or deal with telephone calls.