Trade in refund gone wrong

Hi,

I just traded in an IPhone 8 on a new iPad purchase.

The small print on the trade in said that once I’d made a new purchase and my return was received then the refund would be applied to my payment method.

Credit memo has just come through and the card number on there is a really old one which I don’t have anymore. I had assumed they would refund the card I used to buy the iPad!?

Cannot get through to anyone at Apple to help me with this and currently £140 refunded to an only card which I don’t have.

Any ideas?