Hi

Has anyone managed to sell something as excellent condition and then realised that there is a problem with it? I just sold a 3-piece suit but when I went to package it up I noticed the lining of the jacket was significantly damaged, however the rest of the suit is still in excellent condition. I contacted the buyer straightaway to explain the unfortunate situation and provided pictures of the damage and have offered them a discount if they still wish to go ahead with the sale. If they wish to do this how can I refund them? If they don’t wish to do this how can I cancel the sale which will presumably automatically refund them? 
Many thanks for any help/ advice in advance as I am new to eBay