I never understand it when people say this kind of stuff. Nobody is forced to use a letting agent. If they do essentially nothing, then why use them? You can do the essentially nothing stuff yourself. Or could it be actually that they do do something, hence the reason why everyone uses them?
Have you been drinking?
And from what I can make out from your story- landlord tried to screw tenant unfairly, court saw what was happening, tenant won. So what's the problem?
So someone who's worked their arse off all their life and earned enough money to fund a second property so they can live a comfortable retirement and give their offspring some help on the ladder gets their property taken off them and sold cut price to someone who's arsed about all their life and...
Make all income tax come directly to me. Spend the year building a super villain's lair into a massive floating rock served by a private army of dwarfs with the proceeds. Get a load of bitches to live on there with me. Try to destroy the sun.