Electric back box not deep enough for switch - PLEASE HELP!

[Sazzle]

Hi There, A while ago I bought matching switches including dimmers/ sockets etc for the whole house. When we have come to fit the dimmer switches in two of the recently plastered & decorated rooms it seems that the back boxes are not deep enough by 5/6mm or so. Is there anything I can do rather than take the old back box out & replace it with a deeper one as this I imagine will cause a lot of damage to the plaster etc, I would also have to chip away at the brickwork to get it deeper probably making even more of a mess. Ideally I would really like to keep the same switches as I have bought as they match the rest of the house, there were also quite expensive & its too late to return them to get my money back! Is there any extender box I can buy for the switch etc? HELP... Many thanks in advance.

[TOPSPARK]

As you dont wish to take the back boxes out that you have installed and chip out the hole s to make it deeper for a deeper box to fit the only thing i can suggest is a surface mounted pattress . My other suggestion is very carefully clean aand chip away around the existing box and take it out and then chip away to make the hole deeper for a back box your dimmer switch will fit into
regards
Topspark