Over a year and still no resolution to problem

I was given a faulty iPhone 5S on contract with Altech Autopage Melrose Arch in April/May 2014. After months (and now over a year) of trying to resolve the issue with Altech (including going to Head Office several times when the Melrose Arch branch was unable to assist, sending numerous emails, making several calls and eventually sending a letter with registered mail), I have not been able to get the phone repaired or replaced. When I requested that I cancel my contract and be paid out the monthly device payment, I was told that I had to pay Altech for the remaining 12 months of my contract! No one is willing to take responsibility for this matter, and to add insult to injury, the Altech Call Centre keeps phoning me to try to get me to take up additional contracts with them! I don't know what more to do to get a response from Altech.