Shame on Winkworth, the self-styled “largest estate agency brand in London and one of the fastest-growing in England”. Four young guys rent a property via the agency in Herne Hill, south London. One decides to move on so the others search for a new flatmate. The amount of effort put in by the letting agent and landlord? Almost zero. The rent is pretty steep – £2,450 a month for the house – but the flatmates find someone happy to pay their £612.50 share, and dutifully inform Winkworth.

Winkworth should be grateful the work has been done for them. Instead, its local branch asked the new tenant to pay £835.38. That’s right, nearly a grand to scratch out the name on a tenancy contract and scribble in a new one.

The grubby overcharging didn’t stop there. The local Winkworth agent (it’s a franchise business) said it wanted a total of £1,670.76 as it also formalised a tenant swap last year, despite that tenant already paying a £90 reference fee.

I happened to live in a flatshare in Herne Hill after graduation, in a very similar property just a few roads away. How much did we pay every time a flatmate moved on and we found someone new? Absolutely nothing. The landlord was always delighted we had done the work for him. He would send us the new contract, we’d write in the new name, and that was it. It was also before the era of reference checks. Today the letting agents demand them, which may actually cost only £10-£15, then use it as a device to extract ever more cash.

But Winkworth picked on the wrong person when it tried to charge Will Carter such an outrageous set of fees. Carter is a young lawyer and is used to writing complaint letters. He didn’t get angry, he got even. The letter he sent to Winkworth’s Herne Hill branch, CC’d to me, was beautifully, yet forcefully, crafted – and as a journalist I’ve seen many, many threatening letters from lawyers. The very next day, Winkworth rolled over.

It admitted to an “unfortunate oversight” in how its fees were displayed, and that “we are currently in the process of reviewing our fee charges but our decision has not been finalised yet”. It said it would cut the fee to £210 in total. Winkworth’s head office said it is conducting an investigation, saying “we expect all of our offices to charge fees that are reasonable and consistent”, while admitting that the Herne Hill branch’s fee “is not in line with other local offices’ rates for the same work”. Not that £210 is acceptable, either.

The good news is that fees to tenants are going to be abolished completely, bringing England and Wales into line with Scotland, although for many tenants it is taking an agonisingly long time. The government is consulting with the industry on “action to ban letting agent fees”, but that runs until 2 June, so any legislation is unlikely to come into force until much later in the year and could even possibly drag on until 2018.

Mind you, there’s a nugget in the consultation document that should really please tenants: a call for deposits to be capped. It was standard practice in the 1980s and 1990s for tenants to be charged a deposit equal to a month’s rent; for no reason at all (other than greed) it is now typically six weeks, and sometimes two months. There’s even a suggestion that deposits could be simply held on a credit card (the money is “blocked” but not actually taken), in much the same way car rental companies do when hiring out a vehicle.

In Carter’s case, Winkworth wanted an absurd £2,272.50 from the incoming tenant for a property with a monthly individual rent of £612.50. Quite how young people starting out work, with vast debts from university (now charged at an interest rate of 6.1%) are supposed to ever save for a deposit to buy their home is entirely beyond me. Never has one generation (buy-to-let landlords) been more successful in stitching up another (today’s millennials). The ban on letting fees can’t come soon enough.