Should C&G explain how my interest payments are calculated?

Q I have been trying for some months to persuade Cheltenham & Gloucester (C&G) to explain why the monthly payment on part of our mortgage has unexpectedly changed. Its latest letter suggests it is unable to show me how the revised payment has been calculated because it is complicated.

I don't mind being told I am incorrect, and that the new calculation is accurate - but I do object to C&G's refusal to provide a clear explanation for the basis on which it has recalculated the payment.

JH

A This is a clear-cut breach of the Banking Code. Commitment 2(b) in the code clearly states: "We promise we will help you to understand how our financial products and services work by giving you information about them in plain English; explaining their financial implications; and helping you choose the one that meets your needs."

And an even worse breach occurs on commitment 4.3, which states: "If you ask us, we will also give you a full explanation of how we work out interest." Write to your branch, quoting these two elements of the code, and demanding a full and clear explanation of why your mortgage payment has changed (and send your letter recorded delivery). State clearly that if no explanation is forthcoming within 14 days, you will formally complain - first to the C&G head office and then to the FSA, which now handles mortgage regulation.