In - Received A Letter Stating I Owe A Retainer To Legal Practice I Never Hired

6 years ago, I was looking at having a criminal record expunged. I went to free consult with a lawyer that a friend had recommended, and at the begining was asked to sign a single page document. The document was written without a bunch of legal jargon and was easy enough to understand. It stated that the consult was free, no legal work would be done on my case until a $2,000 retainer had been paid in full, the retainer covered the first x number of hours after which a rate of $x per hour would be charged.

During the consult, the attorney confirmed that the retainer would need to be paid for him to file the expungement paperwork, so I decided against using him. I had another consultation with another attorney who was willing to file the paperwork and attend 1 hearing with a judge if the judge requested to see me in court before granting the expungement for $500. I hired that attorney, paid the $500, signed all necessary documents, and within about 8 weeks, the paperwork was done, approved by the judge without a hearing, and all record of my past was gone from MyCase, and I haven't thought of any of it since until last Friday.

I received a letter in the mail stating that I was in violation of the contract I entered into with the first attorney I spoke to and that I owed his firm the $2,000 retainer. It says that the document I had signed included a passage that stated that I would not hire any other attorney to represent me in that matter. I don't recall that at all. The letter was signed by a lawyer who's name I didn't recognize and have since learned is the son in law of the first attorney I spoke to. It appears that SIL took over the practice when the lawyer I spoke with retired last year.

I left a voice mail with the practice requesting a copy of all documents they have related to me and this case, but what should my next steps be? I wasn't served so they aren't suing me yet, but they did threaten to. Could I really be on the hook to pay $2,000 to a lawyer I never spoke to at a firm I never hired for a case that has been closed for over 6 years now?