Unauthorized debit order

Morning, I'm writing again about Vumatel because of the frustration that I'm experiencing about their poor conduct and services. I'm going to give a brief summary, because I've given a detail description in my initial review. I've app**** for a fibre installation on the 22 April 2025 and 8 days later registered my first complaint with them which was never resolved. On the 05 ,12, 14, 15, 20 May sent them both emails and WhatsApp messages which were blue-ticked and no responses whatsoever. On the 20th May I requested an email address to cancel my contract on their WhatsApp platform and responded by abruptly disconnecting my internet connection.

At the end of May 2025 they debited my bank account, I then went to the bank to reverse it, and they continued to debit subsequent months i.e June, July, August and September. My question to them is, what service are they rendering to me to qualify (them )to debit my bank account because my internet connection has been ceased on the 20th of May 2025?