Billing an amount not agreed upon

The aforementioned property management company has been billing me an extra R100. I have not paid this amount because I was led to believe that they are busy resolving the issue. Also, they do not inform tenants of extra fees they would have to pay in due time as there was an extra Deposit for Landlord fee that I have to abruptly pay even though I was not notified about it. My name is Lazola Booi, I rent UNIT 236 Urban Ridge in Midrand.<br> <br> I would like this issue to be resolved as their billing system is *****.