I have gotten to the stage now where if a buyer starts a return case (aka a **bleep** Slapping) we arrange a return/refund rather than exchange. 

If they want to repurchase a replacement, they're welcome to but once the case it opened it doesn't handle exchanges or sending replacements. It seems to always result in an auto refund to the buyer, even if you've replaced. Then you have to spend hours on it getting it sorted with eBay CS - not worth it. 

I explain that as they have opened a Return case it's Return / Refund as per the case options. There's no option to send a replacement or exchange. 

If they had just messaged me than I could have arranged an exchange but a case is a request for a refund, not an exchange.