SADV - CANCELLATION RANSOM

I signed with SADV in December 2020. The first month was fine, no worries. second month, debit order didn't go off. Had to phone and then it was rectified. This month, debit order didn't go off again. Phoned again, was told I need to make a manual payment as something went wrong. I confirmed, TWICE, that a manual payment has to be made. So I made the payment on the afternoon of 02/03/2021. Come midnight, the debit order goes off. This pushed me into an overdraft with my bank, who actually charged me the full monthly credit fee for a day. Phoned SADV, I have to get the bank to reverse the debit order as refunds take 14 days. So phoned the bank, they charge me again to reverse the debit order that pushed me into the overdraft in the first place. So I decided to cancel with SADV. Sent the cancellation on the 4th of March, and was informed that because it wasn't sent on the 1st, the notice month is April. Almost all the companies I know of that has contract facilities gives at least 4 days leeway in cancellation requests, most give until the 7th. I HAVE to pay for April and they will not release the line before that, even if I make a cancellation payment on the 4th of March. So basically they are keeping my line with Vumatel hostage because I no longer want to use their service. Typical new South Africa company, and I will warn anyone and everyone not to use them.