If you’ve got the refund receipt then you won’t lose the £1,000.
Strange they refunded it to a bank account rather than back to the card…
If, after 8 weeks from your initial complaint, they don’t respond, or you don’t agree with their response, you can take it to the FOS.
So long as they have refunded it, and you have a copy of the refund confirmation then you should be fine. At the very least, they can chargeback for refund not received.