Phone has a fault and not getting any assistance

I took a contract and Cellc Samsung S4, my phone started giving problems within a year, I then took it straight to samsung and it was repaired, 8mnths later it started giving the same problem(it overheats). I then called cellc and ask that they come collect the phone so that they can replace. The people I spoke to at the call centre were just giving me a run around. I then decided to take it back to Samsung. I am being told that I need to replace the battery at my cost. Surely the phone must be replaced as it will be out of warranty soon, I would have paid for a phone that is faulty and would have to carry more cost to repair after the warranty period.