Can a real estate agent charge their own fee for rent not paid on time?

I live in a private rental house my real estate agent is charging me a dishonor fee of $35 when rent is not paid on precise day due I have the rent debited from my account which they claim is the only way they do it but if sufficient funds aren't available on the due date they had charged me a dishonor fee of $35 I did query why they would charge such an amount their response was that is what they are charged through their bank if funds aren't transferred from my account to theirs during the Christmas holidays I received a letter stating they were changing banks and my rent was due on a later day than usual I then thought yay no more dishonor fees but during the first two weeks in January that charged me another dishonor fee of $35 my theory is that it's not legal and am considering taking my queries further any advice would help please for the record I don't intentionally not have rent go through on time but these things do happen