As it says on the sign in the Change Office, it is against the law to change money in any other place apart from a Bank, a Post Office or an Official Change Office. This is why all the jewellery shops were visited by the Police and made to take down their signs. A lot of Jewellery Shop were money laundering and this is why the Government cracked down on it.
Also, if you use the Change Shop in Calis, always ask is this their best rate and can they give more.