Polo 9N: Low Power After Sick Leave & ESP Issues

Good morning everyone.

My girlfriend's car went for its inspection about 4 weeks ago. When she returned, she said the car felt bad to drive. I didn't think much of it at first, but I drove it last week myself, and I have to say that it almost stalls when idling since the inspection. So, those guys messed with it again. My question is, does anyone know anything about the 1.4 TDI 75PS BAY engine and what they might have adjusted? The car is a Polo 9N Highline, manufactured in December 2003, with a 1.4 TDI 75PS engine (BAY).
Another problem is with the vehicle's ESP system. When you start the car, everything seems fine. However, after about 5-8 kilometers, when the engine is warm, the ESP warning light comes on, and the ESP system stops working. If you turn off the engine and restart it, the light goes out again, but it comes back on after a few kilometers. We had the error memory read at the workshop, but it only showed engine errors, nothing else. The mechanic didn't have an immediate solution and suggested we monitor when the light comes on again (about 10 kilometers later). Has anyone experienced a similar problem with their ESP system, and do you have any ideas on how to fix it?
I'm grateful for any tips you can offer. Thank you in advance.

Regards,
Dirk.

Sorry.

With information like that ("the level indicates only a motor error"), it's impossible for anyone to provide constructive help here.

What exactly was the error?

Und das ESP hatte keinen Fehler ? I don't believe it!

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hello,

I will drive to the Volkswagen dealership in a few days and have them read the error codes with their diagnostic tool. Then I will write down the error code and post it here.

Regards,

Dirk.