Payment processing fees charged by the managing agent

To anyone who cares to comment or perhaps has some knowledge on the legality of fees and how they are charged:

What are the rules & regulations for agents who charge tenants fees (in addition to the advertised rent) for payment processing?

Case in point:

I used to rent through a small agent who I could submit direct payments to using a unique transaction ID. I would only ever pay the advertised rent once/month with no additional fees.

I now rent through a large estate agent who uses a ‘smart card’ system. This ‘smart’ payment card simply provides an ID that associates my payments to me, as my previous agent achieved only without a complicated expensive card system. There is a fee charged to use this compulsory card. It is charged directly to my bank account every quarter (separately to my rent which in itself can be paid in a number of ways with even more fees, i.e. Bpay, credit card, etc.).

My concern boils down to this: if the payment card fee is compulsory to all renters through this agency since every tenant requires one, why is this cost not negotiated between the landlord and agent and included in the advertised rental amount? Shouldn’t the rent I pay be inclusive of all such charges whether they are covering landlord or agency costs?

Yes, this fee is stated in my signed agreement, and is a minimal amount, but isn’t it unfair that an agent can charge a tenant in excess of what the landlord specifies, and that the agent can ‘hide’ this cost from a potential tenant by not having to disclose such fees in the advertised rental amount?

I am willing to pay cash in hand to avoid paying additional fees; however this appears impossible.

Regards
Andrew