Broken phone that is still under warrantee

If there was an option of less then 1 that what I would give. I have a contract with cell c which ends in July. I recently in my phone since it was switchin off amd has arror messages about phone being too hot, was not charging and said something about unwanted apps. I then flushed evertything and yet it said same thing. I then boked it and now they saying it an lcd and motherboard which is faulty that I need to pay abou R2000 for something I did not do on my own, what do I know about mother board and all the other staff. My lcd was working fine and I did not break the phone, so what is it then. Im so dissapointed and I guess I do not learn coz it the second time I have been disappointed by them and yet I still go back. What worse is that they said they will communicate with me on the same number that I was using on the phone that is booked, how is that possible coz the phone is with them. Please assist or I will then take it to ombudsman now, I cannot be ********** twice NO! my number now is ***