final notices

Many months ago, I quit refinancing all of my pds's cold turkey. I was over my head and I had just had enough. So I just let them all go. From keeping tabs on different posts, I found out that many of them were illegal and surprizingly enough, very few of them have pursued me in paying....Except for one. It is a storefront pdl company that has turned everything over to collections, etc. I haven't heard from them in a long time, but today, I receive a "final notice" letter stating that if I don't submit full payment by Sept 9, then they will have exhausted all methods of resolution and it would be handed over to attorneys to file suit against me. I have heard that the storefront pdl companys are legal and action can be taken, but the fact of the matter is, I still don't have the full funds available to pay just like when I was trying to keep them refinanced. I live in Texas and am not sure of what I should do. Is this another scare tactic or is this something I should worry about. I've never had any judgements against me and don't have a clue of what to expect if this should go through. Any advice will be greatly appreciated.