NO SIGNAL

I have had the contract with cell c since 2013, in 2015 I received a call to upgrade to a P8 the phone was delivered to me. I have had endless signal issues since then. Logged complaints, had a new sim allocated to me and today I have had no signal whatsoever. I am only able to use the phone via wifi. I have tried to email but there is a 24-48hr response delay. I have used twitter support the last reply was that it is my sim again as I had to try it in another device. All I want now is to get out of this contract, even if it means returning my cell phone. I am a rep and am on the road Mon-Fri. I miss calls as it goes straight to voicemail, while on calls its cuts and today I am unable to even dial Cell Cs support help as the \emergency calls\" is still coming up. Another friend of mine living in the same area also had the same signal issues and Cell C allowed him to return phone and change to prepaid. No more contract No pay ins. Please can I have some assistance with this issue as it is affecting my job mainly. Ps I will glady pay what is due at the end of this month and for what I've already used due end April."