Refund unused postage label.

I sold an item today (value sold £150) and postage used was simple delivery. EBay charged me £3.45 postage and sent me a QR code for label (get printed at post office).

 


Now buyer has told me his address on eBay is incorrect and asked if he could send me cost of postage and I pay for postage with correct address.

 

However I have canceled order - he was refunded £150 - but I’m still charged the £3.45.

 

Now re-listed and he has purchased again with correct address.

 

How do I get the unused £3.45 label refunded that has his wrong address on it?

 

Thanks