Hi here is a letter to send refusing their pathetic offer and demand all your money back hope it helps you. you cant add interest on the amount until you take c/court action. remind them that the amount you want paying back at the moment doesnt include interest,so they should pay you back asap. cheers LES.
DATE}
Dear XXXX
Ref your recent offer
Thank you for your recent offer of £ XXXXX as a gesture of goodwill, I must inform you that I will not be accepting this offer. As outlined in my earlier correspondence I explained that the charges you have applied to my account are contrary to the Unfair Terms in Consumer Contracts Regulations 1999. Further or in the alternative, I believed that your charges are a Penalty.
Penalty charges are irrecoverable at common law. The precedent for this was Dunlop Pneumatic Tyre Co Ltd v New Garage and Motor co Ltd [1915] AC 79.along with Murray v. Leisure play [2005] EWCA Civ 963
Although in my original letter I informed you that I would start legal proceedings within 14 days, as a gesture of goodwill I will give you an extra 7 days to refund £ XXX back on to my account. If this is not done within the 7 days, I will be forced to start legal proceedings, you will receive no further warnings.
The hound V Capital one 
