Buyer claiming item faulty and wants a full refund. Item wasn't faulty when sent.

[tutelary2010]

Sold an iphone 6 in excellent used condition, and included postage in the auction.

Buyer contacted me because the apple ID had locked the phone, which we resolved.

Buyer contacted me again a week later to say that they are having "hearing" issues on the phone. Haven't provided any more details apart from they want a full refund.

In the listing I said "no returns" policy.

Because it's their word against mine regarding the item being faulty, do I have to accept a return and full refund, as well as pay additional postage incurred by the seller (It needs to be insured post, which is how I sent it to them)? What if I get the item back and it has no fault? I have to wear it and start again?

This could be a "change of mind" which I am covered for by having a "no returns" policy.. but how do I prove it?

If I have to accept the return and provide a full refund plus postage reimbursement, can I wait until I receive the phone back?

Thanks 🙂