new switches wider than old ones

[Desie]

I have just replaced two white FCUs with two chrome ones. They sat side by side in a dual fitting dry lining box. Now the units are too wide fo rthe box. How can I change the dual for two singles to widen them by the 1/4 or so inches and not make amess of the wall? The two single boxes will have nothing to 'grab' where the centre of the old dual box was.

Any ideas?

 

[TicklyT]

I would consider using a piece of battern cut to the width of the space between the boxes that can be fed through the hole the box came out of, and fixed top and bottom to the back of the plasterboard with screws through the wall, or adhesive. A scrap of plasterboard or whatever to cover the central bit, and a bit of filler to cover screw heads, and the bit you've filled in. The box will then clamp to the back of the battern.

You may need some longer M3.5 screws for the FCUs, because of the thickness of the wood behind the plasterboard.