Was this ebay? I assume this is the reason for the concern (feedback)
It would have been easier if you had explained you would refund minus the postage and that you wouldn't cover his return costs. I find it's best to make this clear and assume nothing with these buyers
If he now thinks this wasn't part of the deal I suppose he could leave bad feedback as he feels hard done by (rightly or wrongly)
If you're concerned about that try and explain and apologise and/ or refund some more to cover his 'misunderstanding'
Or just ignore him and he'll go away
It would have been easier if you had explained you would refund minus the postage and that you wouldn't cover his return costs. I find it's best to make this clear and assume nothing with these buyers
If he now thinks this wasn't part of the deal I suppose he could leave bad feedback as he feels hard done by (rightly or wrongly)
If you're concerned about that try and explain and apologise and/ or refund some more to cover his 'misunderstanding'
Or just ignore him and he'll go away