Hello, welcome to the website. My name isXXXXX can assist you with this.
Are you saying that they've changed the terms of the mortgage mid-way through?
Thats sounds very odd to me - it's not somthing that should be able to do at all. You cannot change the character of the mortgage from interest only to repayment without your consent. If you, at no time, have given that consent, then it should remain (in part at least) as interest only.
I think you would be on firm ground to challenge this, especially if the repayments are high and difficult to achieve.
okay, I would suggest you write to them first, setting out yout position as you have done for me. Then, finish off your letter saying that if you don't get a satisfactory response, which you would like to be their final response, then you will refer the matter to the financial ombudsman to investigate for you.
Have a look at the ombudsman website, it's very useful, and complaints to him are free to make and he does the leg-work in investigating them for you: http://www.financial-ombudsman.org.uk/
Is this okay? Do you want me to help with anything more?
Yes, you can, you should be able to get them easily enough. If for whatever reason they refuse though (unlikely), the ombudsman can obtain them anyway.