Frustrating dealing with Mweb

I have had an account with Mweb for over two years to provide Internet access and now want to cancel it. There is absolutely no way of getting hold of anyone via telephone or email. I have tried their billing email address 2 different phone numbers that they supply when you link into your account, they send a one time pin and that includes a phone number which I dialed and it eventually cut off. On the second number i got a message that they could not take my call at this time. It is now the 3rd of the month and I have to give one months notice and it is too late for this month so I am stuck now until the end of September or whenever i succeed in getting hold of someone which us impossible