Hi
You need to request for an itemized statement about this account from the collection agency. The federal laws give you the power to ask the detail of the debt from the CA through debt validation. More details about this process are written in this link:
http://www.debtconsolidationcare.com/validation.html
The FRCP laws state that the collection agency has to serve the details of the debt within 15 days from the date you placed the request or else there is NO DEBT.
Sometimes, the collection agents are very intimidating and will often attempt collections on a debt about which the person is not aware of. In order to know whether the debt is legitimate or not, ask the CA to give you the details as mentioned in the link above.
Once you have the accurate picture, make further arrangements with the company and pay it off. If you find that the details given by the CA are not correct, place the item on dispute with the company. They will have to verify it with your lenders before making any further collection efforts.
If you really owe the debt then
debt consolidation san diego can help you from it and stop harassment calls.