Hi Chiptivo,
Dont know if you managed to get your rear brakes sorted, but i had to replace rear pads on a C30 some months ago, in the past have used long nosed pliers to rotate the caliper piston, but found there was no way on earth this was going to work with that approach, maybe you found the same thing, had a look to see where i could buy a windback tool - note these have to have the pins exactly the right distance apart for the calper piston holes.. anyway ended up resorting to making something with whatever i had to hand (will post a picture in a bit) the tool worked surprisingly well as it gave me the extra leverage needed to get the rather reluctant piston to start turning .. had to anchor the caliper on one of the slide pins in order to be able to get the caliper held securely enough to turn it with the homebrewed tool
So like a lot of jobs you only need to get stuck at one tricky point and until you have got past that your stuck with the car on axle stands going nowhere
