Webafrica - problems with cancelling my service and only being able to deal with them via Whatsapp

Webafrica customer number BOF95 (fibre customer). I cancelled my contract with them at end Dec 2022, and they keep on trying to debit my bank account and sending me reminders to pay my account. Although cancelled, my account is still showing ''active'' on their system. I have advised them that I am no longer in the country and the service is not being used but they are ignoring my correspondence They provide me only with an option to communicate via Whatsapp and have no contact phone number or e-mail address . It is very cumbersome to deal with them via whatsapp I have cancelled the contract at end December 2022 and they have still not actioned my cancellation. I moved homes previously, but they keep on insisting I pay the balance of the installation fee although no installation was done when I cancelled the service. I have a full record of the whatsapp correspondence in which they promised to look into the matter, but it's still not done. I may be charged banking fees for the rejected debit orders and may have credit scoring implications if they continue to debit my account. I have to use the bank account and can't do so if they continue debiting my account every month I am aware of the fact that customers have complained about their cancellation process previously and they were instructed by you to provide other channels to communicate with their clients, but they have not changed their process as yet. I need them to cancel my contract and stop debiting my account urgently.