I decided to get a refund. What a poor process that has been.
Managed to get the phone sent back, but then silence. I phoned yesterday, they confirmed they had checked the phone and that was it, done ‘nothing’. Now they want me to pay £8 for postage, so whereas I assumed they would just take this off the refund, they now will send me a link to pay for £8, and then I write back and give them the payment reference, and they’ll process the refund.
Of course, still no link to pay has arrived. How hard should it be?