Phone has not been repaired after 2 months

I sent in my phone (Samsung S4 mini) in for repairs on the 5th Dec 2014, I went in numerous times to check the progress. I have been told that the phone is going to be delivered to me, then I was told that the phone hasn't been booked for repairs, I've also been told that the phone was misplaced. I keep getting different responses from different people. I keep getting told I will receive information and be contacted about my phone, but nothing happens and I keep have to go in to ask. This phone was supposed to be repaired within 21 working days and it is way over its due date, its now the 04 Feb 2015. This is very poor service, I really need my phone back, how can I keep paying for a contract for a phone I don't have.