I was terminated by postmaster supposedly during my 90 day probation but I had actually been there longer than that What to do?

I receved a satisfactory 80 day evaluation on Friday July 20, 2018. On Monday, my scheduled day off, another supervisor called to ask me what kind of evaluation I received on Friday and I told him that all categories were Satisfactory. I thought that it was strange that he didn’t call the supervisor that I had done the evaluation. On July 26 I received a termination letter from the postmaster in a two day express package dated of the 24th but then today I got a letter from the USPS saying that as of July 21 I had completed my 90 day probationary period and was receiving a raise and would have a one year evaluation on April 22, 2019.