Credit Control - LVNV ??

I have been receiving calls from Credit control at work regarding an old account and need some advice. I have spoken to them on a couple of occassions and have sent a debt validation letter which i told them i was doing as i have received 2 letters from 2 different companies on the same account. They sent me a letter stating the following:

Quote:

"Our records indicate that you owe a balance of $XXXXX to ______. Credit Control has been retained by _____to recover the balance in its entirety. Balance is due in 72 hours. This letter is from a debt collection agency and is an attempt to collect a debt. Any information will be used for that purpose."

THey stated this is proper validation. Also, they offered payments that i cant meet or downpayment that i cant meet. Said a decision would be made tomorrow on this account and they would be contacting payroll.

Few questions:
What can they do by contacting payroll (garnish)?
What should i do in the meantime?
The validation letter was sent after 30 days, so are they required to respond?
Any other advice would be greatly appreciated.