Can't retract rear piston on Citroen C3 - Help!

[the pips]

Over the years I've done quite a few brake pads but this one is... well, typical Citroen.
The caliper and pads came off quite easily. Checked the new ones and they're the right ones. Got the piston rewind tool out and found it didn't fit. The piston is extended so far I can't get the rewind tool between it and the caliper.
I've never had this problem before (probably because I've never done a Citroen) and I'm baffled as to how to get the piston in. Anyone got any suggestions?

Cheers
Doug

[WinstonWolf]

Try it without the backplate or g-clamp the plate to the outside of the caliper?

A grinding tool spanner sometimes does the trick.

[Locknut]

I know that Peugeots (same family) use Lucas brake calipers so yours is probably the same. Horrible French rubbish . I presume you are trying to retract the back brakes because you refer to winding them. Can you not get them started by turning them with something else such as a circlip pliers. Then use the proper tool when you move them a little.