Error in connection and network busy

Good day i wanto cancel my contract with the service provider because i can not use the phone because of error in conection,network busy!!!!!! and if people try to call me they struggle to get thru, my remaining period is 14mnts and to cancell the contract i must pay R4199.00 my phone is R313.00 per month that come to R4382 so i see i must pay the remainder of the contract anyway without getting any thing?