The advertising watchdog has clamped down on hidden costs for theatre tickets, ordering sellers to be up-front about compulsory booking fees.
The Advertising Standards Authority has ruled against four theatre websites - the Ambassador Theatre Group, Charing Cross Theatre, the AKA Group's site for the production A Chorus Of Disapproval, and The Old Vic - for displaying misleading ticket prices.
The websites drew complaints that advertised prices were misleading once booking fees or transaction charges for phone and internet purchases - around £3 - were applied.
The ASA's rulings mean advertisers will have to make compulsory charges clear in the ticket price and will have to be up-front about fees that apply per booking.
The Old Vic said it had added text to the bottom of the page which highlighted the amount of the booking fees, but pointed out that the fee was per transaction rather than per ticket.
But Charing Cross Theatre said it was not reasonable to require them to include the commission fee in ticket prices given online because the website was also a reference point for those booking in person at the box office, where no commission was payable.
ASA chief executive Guy Parker said: "The ASA is clamping down on misleading hidden costs. Today's rulings about advertised prices for theatre tickets make clear that sellers must include all compulsory fees and charges in quoted ticket prices and be more up-front about booking fees.
"Our priority now is to make sure our rulings are followed by all ticket retailers.
"These pricing practices are simply not fair. They draw us in on a false promise. They make us less likely to shop around for the best deal. Our rulings send a clear signal to advertisers: sort out your pricing so we all get a fair deal."