Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
if there is a substantial change in the itinerary or the host service needs to be cancelled , airbnb will work with the host to provide guests an alternative date for the host service , an appropriate refund or a rebooking . 

```
. OPTIONS: ['Contract by using' 'Unilateral termination' 'Arbitration'
 'Unilateral change' 'Jurisdiction' 'Content removal'
 'Limitation of liability' 'Choice of law' 'None'].