My question involves collection proceedings in the State of: Maryland

My question is regarding a debt that I tried to include in my debt management program. My husband lost his job in March so we fell behind in paying our bills. We've since separated and I am re-paying all of my debts at this time. In July I enrolled in a debt consolidation program and have been paying on my bills since July. Unknown to me one of my creditors would not accept the payment and apparently sold my account to a National Enterprise Services (NES) so my payments have been going to NES but my balance isn't going down. I contacted (NES) recently and was told that unless I send them a $1,000 down payment, they will not accept any more of my payments and am going to send my account to their attorneys. I currently owe them $4,286 and have been sending in $85.00 each month. I belive this to be a very fair amount and am not even paying some of my other creditors that amount. Can you give me any advise on how to handle this? Thanks in advance.