Discussing service from city property

I am utterly tired with city property bad mouthing me and tarnishing my name and as a result I am struggling to get accommodation.

I served my notice directly to the building manager in August 2019 indicating the I will be moving out end of the month as I was relocating due to employment.

For some reason he failed to submit this to city property head office and I also found this out on the day of moving as the security guard needed a later stating that I can vacate the premises.

I spoke to someone at the head office and such letter was provided so I proceeded with moving out.

Fast forward to today they are now arguing that they gave me a notice to vacate the premises due to defaulting of payment which is totally wrong.

They say I left the unit at a bad state which is absolutely incorrect. As a matter of fact when we called the building manager to do the out inspection he advised that its fine the is no need to do it we must just leave the keys with the security as he is not around.

I have asked for proof for the above and the statement that they have sent to me indicates that I never missed any rental amount.

In addition I have requested for proof that a notice was sent to me that contains the exact date and they failing to provide it to me.

I am now being told that they are investigating the matter.

So how does a so called reputable rental company like city property give out false rental references without having their ducks in row.

I need this be resolved asap and a retraction statement must be printed and an accurate references given stating that I never missed rental payment and that I gave them the notice not the other way around.