WORRYING CUSTOMER SERVICE

sometime in December they did not debit my account then wen i told and proved to them that there was money in my account they claimed since it was from an overdraft they couldn't debit and honestly that was none of my business as money in my account is money in my account. i have been getting calls from them but funny whoever is calling won't speak or will be chatting to a colleague while i keep saying hallo, now i got an sms stating i did not honor my promise to pay 3321 which is actually the monthly debit amount, and the debit went off on the 25th what is making me angry is the fact that the sms itself is so threatening and bullying, PLEASE GET YOUR BOOKS IN ORDER AND STOP THREATENING CUSTOMERS I REFUSE TO BE BUL****