So, just got a follow up letter to the original...note not a response to my letter that I sent to them, but another automatically generated letter looking for the money.In this letter they extended the expiration date for when payment is needed to October 30, 2020."A previous request was made for the return of the overpaid amount, without resolution. We ask you respond prior to October 30, 2020 so that we may correct the 1099 tax document details before the end of the year."Note I did get access to my old 401K statements and it appears that at the end of 2017, I was only 67% vested in the contributions matched by my employer, thus since I received payment on Jan 8, 2018, it seems like the are probably correct. One other note, the distribution was made via check from my previous employer to Fidelity.Now what should I do?