Worst service ever

I have signed up for the Cell C fiber 20 mbps upload and download since middle of August 2018. I've noticed every evening the speed drops and the internet is inconsistent and decided to send an email on 12 November 2018. On 13 November a technician Mr Gillion phoned me regarding this , he informed me to change a cable which I did. Tell me to unplug the router and the problem is supposed to be solved. It was not solved the problem persisted.

I informed him and sent him a copy of a speed test . He informed me that he will try and send a technician. After 8 emails with numerous speed test results to a person named SITHOKOZILE MAGUBANE and receiving 2 case numbers as well as phone calls another lady S Meyiwa informed me to send her 3 speedtests to her email on 26 November. Needless to say , up until now I did not receive a answer on my email , not a phone call or a visit from the technician.