Injection pump defective or not?

Last Thursday after -15 degrees frost the car did not want to start, battery empty. After changing the battery the start engine did not start. The car was towed fom FOH. Diagnosis was a piped diesel filter. In the afternoon the car was brought back and parked. The next morning exactly the same problem. to be towed again to the opel. but now it was according to the FOH the injection pump repair of the pump estimate 1950 euro or new Pu mpe with installation even more expensive. I was able to fetch the car again because he ran again while picking up still the error codes fragd: P0002 fuel volume controller – range/function error circuit P0562 system voltage- too low The car once turned off for safety in the garage. This morning tried to start again and ran without porbleme. I actually only know fault of the injection pump as kaput or not kaput. It was also much clearer there. The engine went off, engine malfunction lamp on and no longer running. At that time the pump itself was upgraded, overhauled at Bosch (about 500 euro ex VAT) and re-installed. So I don’t quite understand why the FOH wants to have 1500 euro for the installation and expansion, everything was only 4 hours work together. what do you think about it? continue driving or repairing it? Opel Omega 2.2 dti 210,000 km bj 02-2001