Sorry that I've only just seen this, chanel5.
If the MCB (breaker) is cutting out, then it's a short circuit problem. Somewhere, the live and neutral are shorting together. (I doubt if this is an overload, which would have the same result.)
If it's the RCD tripping, then it's an earth fault (live cable is shorting to earth, or the neutral cable is doing so.)
A little bit of simple fault tracing is needed. Any half decent electrician would be able to locate the fault.
Your problem is that you do not have a competent electrician on the job.
The only answer is to ask around for someone who really is competent, I'm afraid.