If a company offers a refund in writing then offers a repair can I insist on the refund offered?

Busterme

I bought a wetsuit online from Huub wetsuits. I wore it under 20 times and splits appeared. I contacted them and they offered a repair. I checked trustpilot and other swimmers have had the same issue, so I returned the suit with a request for a refund ‘suit not fit for purpose’ It was about 7 months old. I received an email from Hubb saying my return had been received, followed by an email saying my refund request had been approved. I was awaiting my refund when they told me my suit has been repaired and I need to pay the postage to get it back. Can they back track on their ‘refund request approved’ message? How do I get the refund?