It is the sole purpose of collections to collect. When the party in debt brings something out to counter collecting it can become a boxing match between two pitbulls. At this point, you need to know the reason for staying persistent in getting the funds. You need to know to defend yourself when things escalate. For now, it is suggested you copy the contract signed by two people and send it with a letter stating the matter is resolved as indicated by the contract of which you are sending a copy of. Anyone else that treats you as persistently as the collector, send a copy and tell them to contact you no further.