Am I being hacked

I've been a tenant on one of their apartments and I field a notice of contract cancellation since I had bought myself a house . I emailed a notice on the 1st on November 2021 and moved out on the 1st of December 2021 with all the documents being completed as per the care takers request.

On the 13th January 2022 which is today , I received an email telling me that I am owning a one month rent which I do not understand because before sending a notice on the 1st of November 2021 I paid my the rent on the 30th of October 2021 .

I still have a hard copy of the lease agreement and they is nothing that explains to me how did I get to owing them. I am reaching out on them to findout and I am struggling to get somebody to explain to me in details.