After receiving a refund (for a significant amount) from a item brought on Ebay, i waited for the usual 3-5 working days for the amount to clear back into my account during this time it displayed as pending. On the 5th day the amount had still not cleared and all records of the transaction had disappeared from my account. I phoned them immediately only to be told that your transaction has been 'lost' during a technical error and we don't know when you'll receive it. It is now over 30 days since the transaction and i am still without my refund, if this had occurred with my bank or credit card company the monies would have been refunded straight away. I am pretty sure this is in breach of FSA regulations.
So avoid if you can but seeing though they're weaved into almost every online shop its not that easy!