Thread of blacklist Mtn not doing their work

The month to month has been canceled and the router returned 13/06/2024 Ref nr IRMS*** after I phoned 30 May to cancel the package and was told I don't need to cancel. I have send emails but nothing. I even went back to the Mtn shop in the Waterfall Mall in Rustenburg. I even got a reference nr that the route was received by Mtn. What more must I do if Mtn staff do not do their work. Now they are threatening to blacklist me for the payment for August that went through 4 July but the router was returned and my account paid up for July when I returned the router 13 June 2024. The take the payment the previous month for the next month. I cannot reach them via phone and WhatsApp says I must send an email that I did... What now...