An impudence of the workshop (Rosselklappe)

Hi all, I brought my mitsubishi galant into reperatur, he always went out in empty run, but worked under load perfectly. the workshop meant throttle valve defective. he said you had to swap was a error code in memory, it costs 842 euro + VAT. he then needed whole 5 working days to get him to run again, he said he calculated me 4 hours + flap. well I thought if he goes again that’s ok. I picked him up and then the hamm he, 1789 euro, throttle valve 928 euro 6 hours time, oil change (was necessary because of an addition of cleaning agent for the injection nozzle he said to AGGRESIV ) and ignite candles. and now the hammer, the problem still exists, he has always died from me in the distance of 500 METERS during the decoupling, he said ” you have to drive 100 – 200 km and then is good ” there is in this LAND at all still a handcrafted honour ? NO ……. and competent dealers anyway not 🙁 i am upset that a i’m going to have my throttle valve tested at ecu.de (has someone already had experience with the company ?) in order to be certain if the old throttle valve was not in order. what possibilities do i have if the throttle valve was in order ? and what problem could I have ? has one a council ? I thank you in advance for every tip cu all