Debited for Someone else's contract

This is the 2nd time that Cell C has used my banking details for a contract that does not belong to me.. Did I give permission to have my account debited NO...did I give you permission to then hand over my details to a debt collection company NO....so can you tell me how *********** are you as a service provider. So now I have the pleasure of making phone calls to various departments to sort out your mess up...you have absolutely no regard for peoples time and also what makes it even worse is the fee's that I now have to pay. DISGUSTED. Since your pathetic company has made my start to the new year so miserable I will now be changing my network.