Wahooooooooo!
They phoned to negotiate (offering £250) and I said I was only going to settle for a Full refund of £277.50. He said if that's the case, they will credit my account with £277.50, (not admitting liability - of course!)
Result!
Thanks for all your support, I feel GREAT!!
I did record the conversation too, I think I may go and watch it now. . .