Loss of brake pedal: This condition is usually a result of brake fluid leakage due to failure of a brake hose or a rusted metal brake line, a worn wheel cylinder or brake caliper, or a worn master cylinder. A simple once over of the system will reveal what's going on.
If you have questions about a specific purchase, it would be best to speak to an attorney who could inform you of your legal options. While there are laws that allow for a 3-day right to cancel certain purchases, these laws are very specific and do not apply in a majority of consumer purchases.
Canceling a purchase on eBay can be tricky since the sale is considered final even if you haven't yet paid. EBay has a formal cancellation process that allows you to contact the seller directly and ask him to cancel the order, but the seller must cooperate for the process to work. If the seller refuses, you must either go through with the purchase or risk getting a strike against your eBay account.