Citroen C3 not known

While travelling on the motorway the vehicle suddenly lost power down to 20 mph
and broke down the problem showed a diagnostic fault.
The car was checked by the garage from which it was purchased and the dioagnostic fault was rectified and a new clutch was fitted. The next morning the car left for London but within 25 miles problems occurred with the radiator overheating. It was checked and it was found that the power supply panel was hanging down the front of the car near the radiator and a lid was caught down the back of the fan On arrival back home it was again checked at the garage and it was stated that the fan was jammed and it needed replacing this was done but shortly after the light was showing again and the car lost power the car was diagnosed with several faults this time the throttle was said to need replacing which was done, and the electrics were reset. soon after the same fault occurred sometimes the checkshowed faults sometimes it did not the garage had no idea on what to do next All together since March the vehicle has had a clutch fitted, track rod ends, radiator fan New throttle Cam belt and bulbs replaced plus a number of diagnostic checks. At a very high cost. we are at our wits end on what to do next and still it loses power