money debited on paid up account

This company is a true ****,

I paid up my credit card account with them but they debited my account at month end with the installment amount.

Now i have been trying to call and get this money back but no one can help. No one understands what is wrong?

i dont get why such companies exist...all they do is take people's money. Standard bank should also be held accountable for sending accounts to *******.