I deserve a serious technical Attention from Cell-C to resolve connection problems

I got a new router Zyxel and I have had one problem after another, from one technician to another promising to end my poor quality internet and unstable connection, and one update after another without success. I am tired and I would advice Cell-C to either replace the Router with proper working one and send their technician this time around to do it physically or I will really be forced to look for a new service provider as I am angry at this point. I pay a lot of money to be receiving such a poor internet and service. I do not understand why I never had a single problem with Technicolor Router for years until it broke down, and now a new Router is giving serious problems in less than a month.