UNFAIR SUSPENSION

I cancelled my service with VOX Telecom 19 July 2023. I was told there is a cancellation fee and I need to pay for another month which will be August. I received a FINAL DEMAND and my wifi was cancelled (no connection) on 24 July 2023. I am paid up in full untill end of July and I still need to pay for August. So please tell me how they can send me a final demand and cancel my wifi on the 24th of July? After several emails and holding on, on a line for more than 35min with no answer, I was told the following: "please be advised that upon cancellation you are required to serve a calender months notice. This was not paid therefore the account was suspended due to non payment". The calendar month is August and is only payable on the 1st of August.