Parts purchased from AutoMirrorsExpress.com can be returned for any reason, so long as you are within the allowed return period for your order. If the return period on your order has expired, then you cannot return a part for any reason except warranty exchange and manufacturer defects, even if you don't need the part anymore.
If the part hasn't been shipped out yet, there is a 15% cancellation fee. This is to help us cover various fees we pay, such as bank fees we're charged on your original transaction.