MWeb won't let me cancel my internet account with them

I am trying to cancel my internet account with MWeb because they keep increasing my debit order so I don't have enough money in my account to cover it, Then they cut me off, and send a notification to reconnect (which I don't receive because I have been cut off) so I have to pay a reconnection fee! They charged me sometimes on the 1st of the month and sometimes on the 15th so I did not know when to put money in my account to cover the charge. There is no option on the MWeb website to reject cookies so you have to accept them in order to make any transaction. There is no longer an option to log a query online. There is no email address. There is no WhatsApp number so you have to phone and use airtime or chat. I got through once but my airtime ran out and they would not call me back. Every time I have called their Sales number since then to tell them I want to cancel my account, they put the phone down as soon as I state the reason for my call. If I use a Chat, it is unanswered, even though I wait for hours. I have saved screenshots to a Word document to prove this. There is a story online that, because payment is in advance, even if you manage to contact them, you have to wait till a month after you have paid the last debit order, which has to be after the request to cancel, before the debit order and the service is cancelled. I have tried to do the cancellation in a polite, businesslike way but it seems the only thing I can do is get another service provider and keep reversing the MWeb debit.