Handed me over to their debt collectors for an acc

Good Day , i still don't understand howcome Altech Autopage handed me over to Nudebt saying that am in breach of contract, i have requested a settlement amount for the amount i owe Altech and got the Rand value, i paid the full amount as per their settlement letter and they then send me a confirmation of payment.<br> <br> What is it now that am in breach of contract. Somebody please help.