Downtime and unable to take my calls

We have 2 contracts taken with the cell c and mweb lte... I call but never get through to billing. I explained that we depend on the lte being active in order to receive voip calls but now with cell c being constantly down we are srruggling. I called and explained this bit billing takes forever to answer. The lady I spoke to prior told me that maybe they would assist in cancelling the contract without penalties because she understands our frustration. I've had so many contracts and it's the first time in my life if like to cancel. We cant keep calling mweb to hear cell c has a problem... I now have to resort to hello Peter because they don't even have an email address noted... I want to cancel this contract due to bad service ... downtime is hours and almost full days... it's detrimental to our business