Terrible Network without the worst signal!

I've been with CellC, Vodacom and MTN before but this is the first time I've experienced such a bad network. The only reason I signed up with Telkom is because they confirmed their network was backed up by MTN and i was on MTN network before moving to Telkom and never experienced any network issues. Everyday since i took out my contract I've had an issues with my network. Either the Network is busy, no reception, data roaming, people can't get a hold of me, call goes straight to voicemail, calls cut, bad call quality were either i can't hear the other caller, they can't hear me or both. This would be understandable if I lived in a remote area but I work and stay in Sandton where their coverage map shows full coverage. I have even been to there stores to complain and they told me as off 1 December 2018 they moving to Vodacom. This has not helped at all. I get 5GB of data and 350 minutes per month but it's not worth having because I can't use the data because of poor signal 90% of the time and the call quality is soo bad i rather use my landline. Defeats the purpose of having a smart phone or even a normal mobile phone if you on the Telkom network!