Unstable signal, Unprofessional service

I have been using Rain for the past year and a half. I'm on the Unlimited 4G package for R479 per month which is supposed to have up to 10mb/s download speed. I have never had 10mb/s download speed but it was good enough for downloading games or programs(between 0.2kb/s and 1.2mb/s, as the signal is very unstable) and streaming movies. February I had to lodge a complain with Rain after the signal became so bad that I could not even stream a movie without constant buffering. They gave me a call and after explaing the problem to the technical department, the signal was better the next day but it did not last long. I have been patiently using the very unstable wifi untill about a month ago when the signal went from very unstable to unbearable. I lodged a complaint again about 3 weeks ago.....no answer....not even an acknowledgement of receipt of my complaint untill today(16 July 2022). I find this very unprofessional from a major internet service provider. I can not continue to pay for a service that I can not use properly. I am currently looking for the best alternative service provider so that I can switch. PS. The problem is not on my side as I have got a good router. I have tested other network SIM cards in the router and they work 100%.