MWEB - Pathetic service and unreachable.

I am trying to get hold of MWeb for the past month. First off their app is completely dysfunctional and does not link your account details. Secondly, I tried to get hold of MWEB because they CHOSE on my behalf that I need a faster line at an increased price. I would like to cancel my subscription/line/account with MWEB, effectively 30 June 2024. No more billing from the 1st of July. I would like to be re-imbursed for all the months I was charged for a 200mb line where I clearly chose a 100mb line.