Rude and Arrogant consultants of MBD

I had an cheque account with Standard bank and closed the account,They've handed me over to MBD. The consultants are rude and arrogant. I've asked them to send the statements of me owning Standard bank they can't assist me. They calling me everyday on my work telephone I've inform them that I can't take private calls during office hours,But the lady was arrogant and rude She will call me everyday on my work telephone. I don't know what to do,because I can't pay an account that are closed and no prove can be given to me