Send another letter by email and in the subject box write "Formal Complaint". Then print the same email and post it to them making sure you write "Formal Complaint" at the top of your letter. Make sure you send it by "recorded signed for" at the very least. If you still don't get a response report them to the Financial Ombudsman at [email protected]. In fact if you want to be extra cheeky then CC the email you send to the Capital Finance One scumbags to the Financial Ombudsman as well. It seems they won't respond because the want to extort as much in charges as possible.