Terrible coverage and service!!

I was forced into taking them on as a service provider when I moved into the complex I live in in Cape Town. I have had issues since, coverage is not steady most days, I do not get coverage in my bedroom even with a Wi-Fi extender (mind you I live in a two bedroom), the most recent issue I’m having is I cannot access any browser on my phone or laptop and whenever I report any issues to them they don’t seem to see any issues on their end. I have tested the speed of the internet numerous times and it’s slow but they refute this.