I had a very similar experience with a different company (but essentially the same thing). I contacted trading standards and followed the protocol of sending three letters via recorded delivery the last one of which was a notification that I would be taking them to small claims court if they hadn't sent the refund within two weeks of the letter date. I was just starting to fill out the small claims form online when a cheque dropped onto my mat. Keep pushing, keep asking and follow the process. Too many companies adopt those rude and bullish tactics knowing that most people will just give up, which is why they keep doing it because they keep getting away with it.