Incorrect billing

I have moved out of Mafadi property(Palm Springs) on the 03 October 2020 after serving my notice and my contract with Mafadi expired. To my surprise I was contacted by their lawyers and advised my accountant has been handed over to them as I owe the full October month rent and even after I have explained to the caretaker that I will only be able to move out on the third and he never mentioned that I will still be reliable for the whole month rent if I don't move out on the 30 September 2020. Mafadi has never contacted myself or shared any monthly statements stipulating that I owe October rent. This is now affecting my credit records.