Most letting agents are well aware of (and compliant with) the legal requirement to display the fees they charge tenants, to help find or move into a new home.
However, quite often, agents and the landlords that they work for don’t know about the agent’s responsibility to display the fees they charge the landlord.
If you are a landlord and want to employ an agent to act on your behalf – the law says that you should be able to see, very clearly, what you will be charged before you actually decide to use their services. The information must be visibly displayed at the agent’s business premises and on their website (if they have one). You can find digests of the rules on the websites of the different agent/landlord professional organisations. The legislation itself is part of the Consumer Rights Act 2015 and you can find the relevant sections here on gov.uk.