Tracked Returns, possible to get a duplicate receipt?

[Viaduct]

This is entirely my fault as I misplaced the receipt from the post office but is there any way for Royal Mail to issue a second proof of postage? Or confirm the address a parcel was posted to?

I posted a return and it says delivered to NDC, as addressed, five weeks ago but the company is claiming they haven’t received it. (I think the underlying issue here is the company sent me the wrong item in the first instance).

I generated a returns postage label online through Royal Mail’s tracked returns portal, it issued a prepaid returns label to print off. I still have the confirmation email and return label on my computer but the company won’t accept it. Online it shows all the tracking events so I know exactly when it was posted at the post office, the service used is Royal Mail Tracked Returns 48™.

The post office cashier scanned the QR code when I posted it, surely they must cross reference the address? Does it show on screen? The recipient must be saved on the system? Do they check addresses when doing delivery scans?
Clutching at straws here but is there any hope?