MTN ***** your money

I subscribed to a new data contract on 14 May 2019, after no internet access in our area i contacted mtn and told them i want to cancel the contract as our area does not have reception. I did that on 17 May 2019. They told me it will cost me R309 to cancel the new contract and i have to pay this into MT's account and send proof to them, i did that on 18 May 2019. On Monday i asked them when will the contract be cancelled and only on 21 May did i recieve a email confirming the contract will be cancelled and my sim has been migrated back to pay as you go (i used my own sim). MTN deducted R378-62 from my bank account 26 June 2019, i phoned them and asked for what as the contract is cancelled, they could not tell me, saying it is for services !! I want my money back and an explaination why they took money out of my bank account but no help from them.