I hope someone can advise me please. 3 years ago a friend got a mortgage of 235000 to purchase a property for me to rent from her while I was waiting for my seperation to come through (still waiting). Part of the loan was put on to her existing mortgage and the balance for investment. I was paying 1200 per month she has now told me that it should I should have been paying 1657 per month and not only do I now owe her 3 years back money but have to face this big increase. I had hoped to buy from her and still do. We will work the method of payment out but she has never claimed TRS nor have I claimed relief on the rent and I don't know if it will make any financial difference to either of us. Please advise and thanks in anticipation. (she was working abroad and only noticed the payments when she returned recently).