They are probably either trying to vacuum bleed it which simply won't work, or bleeding it with the pedal which is very high risk on a 20 year old car as any moisture or corrosion in the far travel of the master cylinder (inevitable in D2s which seem to mostly have brake fluid like seawater) will trash the seals when you press the pedal to the floor.
The solution is to pressure bleed it with 2 bar of pressure required to get through the ABS unit. You have to have a proper tool for this. Good luck to anyone trying to pull 2 bar of vacuum
Just changing the calipers doesn't need the ESP pump bleeding, but if they have let it run dry it'll need basic settings running on the pump to cycle the fluid through.