Totalsport review: A phone

I bought a phone at Totalsport around September it's started giving some problem in 3 Months then I took it back to the store... they took it back saying the software might be the problem they will send it to be fixed... after a month I went back the the store to check if the phone was Okay I got there I found that the phone was there and it was fixed then I realized that the phone was open at the back and they took it back immediately from me saying that they'll have to take it back again to be fixed it's been two months now I just don't understand why is it taking so long for the phone to be fixed "software" still don't understand why was the phone opened from the back... please help