Poor Internet connect

Been a client with Mweb for a week and its sad to say, but the Fibre is very bad. My line cannot evens be stable for an hour. I have made numerous calls within this week to Mweb to be told that they sending a case to Vuma but then Vuma tells me Mweb has to sort it out. My son needs this line for online classes and i have to buy him now prepaid data and be a looser of a subscription i am paying Mweb for no internet usage. Please advise how to cancel with Mweb???