"I am a test enginner in fuel systems working for a major German company. and anyone tells you that it can be cleaned, he is FULL OF CRAP. The best thing you could do to the injector to clean is remove the carbon from around the needle (for digital injectors)."
Again, this is a CIS injection system. Since it is not direct injection, I don't see how carbon can form unless intake backfires are a problem. Since the injection is continuous, there is nothing 'digital' about the injectors - they have an input check valve that should shut down at a specified minimum pressure, and an outlet valve that agitates and atomizes the fuel. Either can malfunction due to residue and can be cleaned, though only with specialized fittings and equipment. Since they are mechanically much simpler and cheaper to make than solenoid injectors, replacement is probably cheaper than the cleaning charge would be, if they are faulty.
Also, if you are referring to cleaning the rest of the CIS system, cleaning can be a very successful repair and diagnostic. Unlike the case with pulsed injection, which mechanically is comprised just of a constant pressure regulator and fuel supply tube. With CIS, the airflow sensor/fuel distributor is more mechanically complex even than most carburetors - and as likely to gum up and profit from cleaning.