Do not change your type B mcb;'s
These are the correct type for a domestic installation (resistive load) other types (C&D) are for inductive and capacitive loads normal found in the industrial or commercial sector.
It could be the motor/compressor in your freezer. Isolate it or put iit on a non rcd protected circuit then see what happens.
Failing that - call in a sparky - give some nice sparky in your part of the world a nice job. Make him tea, give him a bacon butty and don't baulk at his bill!
NWC
March 2008