Brandt fridge/freezer not cold or freezing?

My fridge/freezer gradually died down. At first it would come on, be cold adequately for a day and then stop (i.e. no fan/motor noise) even though the light would come on and everything would defrost. Now it is not working at all, but there is power. Engineers are telling me it could be the compressor/relay in compressor, the condenser, motor etc. all of which would cost me the price of a new fridge/freezer. Is this right and is there anything I can do myself?