livid customer

If there was a zero rating I would have rated them that...I was told that there was a promotion if I was interested in settling my account and I took the offer and paid them as agreed. After a year with few months I am receiving a call n SMSes saying that I owe them R500 and some odd and they have handed me over to the attorneys/debt collecting company ..I am livid with their service they wont get a cent from me