A dirty trick indeed - the name will be of course of use but the lesson to impress upon people is that if you don't know the shop, use only licensed change offices. I'm more than happy using a silver shop in Calis (Onur) but we know the owner and if he's going to rip us off he's playing a long game!!! Please, if anyone gets the chance to help people, send them to a bank or change shop, not a shop that sells something else but has a "change" sign too.