Don't be afraid to talk with the collector. But first, ask them to introduce themselves, present their passport, a letter confirming his / her powers and assignment agreement (the original) – the assignment of rights of claim of the debt. If he refuses to give you your data and documents, just stop the communication.
If the collector politely introduced myself and began to lay out the case, listen carefully to him. Ask questions if you have any. Ask the collector to show the original document, based on which it requires to repay the debt. If one is not submitted, you have every right to qualify the actions of the collector as extortion.
If all the necessary documents you shown, including the original power of attorney, take the time to determine whether the authorized come to you the collector to commit the actions that he conducts or intends to conduct. That is, compare what is written in the power of attorney, with what and how does the collector. For example, he tells you that you have prepared all the appliances, after which he will withdraw it on account of your debt. Such authority, he certainly can not have, because inventory and seizure of property is possible only by court decision and solely bailiffs. However, ask the collector to show you the paragraph in the power of attorney under which it imposes on you such demands. If a point in the document (and it can't be by definition), you have every right not to obey, moreover, is to call the police or invite witnesses.
You are wise, if all communication with the collector will be locked. Use the video and photographs, the recorder, the individual functions of the mobile phone. Well, if you start your conversation will be held with witnesses. Demonstrate your knowledge of the law and your rights, stating that all records can be in the Prosecutor's office. In this case, your statement should not be threatening. Try to stay correctly, not srevices rudeness and insults.
Do not get lost and do not start to make excuses, and especially to cry in response to pressure and brutality. Rights to recover the debt from the collectors is not more than other, completely innocent people, because collection agencies are not law enforcement. Their representatives are behaving sometimes so unbridled, using psychological pressure on the debtor, being confident of the legal illiteracy of the population. Often their tricks really work. That's why laws should know.
If the arrangement initially adopted be negative, the collector threatens you, blames the cheating, insults or humiliates, feel free to call the police and write a statement.
In no case do not put their signature on any documents. Say that you want to show them to a lawyer.