I had a similar bad experience with them and have also not yet gotten a refund. I filed a complaint with the Better Business Bureau, but I don't know if you have something like that in the UK. In any case, I looked at the BBB records and there has been over 40 complaints filed against Betterbodz and most of the time the business didn't reply at all, so maybe it's not helpful at all.
If it makes you feel better, they owe me over 150 dollars.
I'm still looking into ways to get my money back, and it looks like there are a lot of other people in our situation. Let me know if you make any progress. I don't want to give up on these crooks!