Product: Debt collection

On XX/XX/XXXX the Mortgage Loan Officer with whom I had been working since mid-XXXX XXXX sent called me to question the nature of some collection activity associated with my account. The {$1500.00} debt to XXXX did not at first seem familiar to me at all ; this was the first time I was alerted to this matter. I explained to the Loan Officer on the telephone, and later that day in writing the matter was, related to a mobile telephone and line of service I allowed a friend to open up as an adjunct to my own account. This individual fell behind in the payments on the phone/account. The debt was from XXXX, and the friend was eventually XXXX. That explanation was satisfactory to the loan underwriters. 
Unbeknownst to me, Southwest Credit Systems , LP, a debt collector, had sent a letter addressed to me to my friend 's home in Michigan demanding payment of the above debt. I do not live in Michigan, nor have I ever lived in Michigan. My friend who lives in Michigan is now a XXXX XXXX XXXX, and I work for her. I do not, nor have I ever received mail this or any other address in Michigan. This letter lay in a stack of mail, unopened, until XX/XX/XXXX. 
On XX/XX/XXXX, the day before my home loan was scheduled to close on XX/XX/XXXX, the loan officer called me again, explaining my credit score had now dropped a large amount due to the XXXX debt mentioned above. The loan officer and I together phoned Southwest Credit Systesm, LP using information the loan officer had pulled from my credit file. We spoke to a customer service agent who was unable to answer our questions as to why the letter explaining the charges had been mailed to my friend and employer 's home. We were placed on hold in order to be transferred to a supervisor and the call was eventually dropped. 
On XX/XX/XXXX, the following day ( when my home loan was to have closed ) we called Southwest Credit systems again. This time we spoke with a supervisor. He informed us that the company had mailed the letter requesting payment of the {$1500.00} XXXX debt to the Michigan address of my friend on XX/XX/XXXX, and had recorded a collection against my account for the same amount FIVE ( 5 ) DAYS LATER on XX/XX/XXXX. Our request was that the company remove the collection record from my credit file while we discuss and try to reach an agreement on the question of the old debt. As I mentioned above, I had only recent become aware the debt still existed... and only the day before my home loan was to have closed did I learn the matter was being actively pursued in collections and had effected my credit score.

To summarize : Southwest Credit System, LP sent a letter demanding payment for a very old debt to XXXX. The letter was addressed to me but sent to an address in Michigan of a friend of mine, an address where I have never lived nor received mail. Only 5 days passed between the date this letter was dated ( XX/XX/XXXX ) and the day Southwest Credit says they reported this collection. As such I was and have so far been unable to investigate the details of the debt in question nor dispute them. Meanwhile, my home loan which was to have closed last week has been held in limbo while I try to get to the bottom of this collection matter which popped up suddenly and mysteriously and at a moment when it may have done irreparable damage to my life.