Ok, will do then. Just a quick email with basically the same idea as here. Wouldn't heart too much I guess. Just not planning on any legal action or something. If they'd like my signed statement, I'd be happy to give it to them. Though not ready for any court testimonials...

You're right... If they would be honest and state that they have a service surcharge, then it wouldn't be of any problem. Though lying to tourists isn't the way to welcome guests into your country/airport.

On the other hand, they might just stop selling sim cards and oyster cards, which will result in a worse situation for tourists. Although I hope that it will not go THAT far.