Fabia 1.2 TDI - Intake manifold issue.

Hey! I've been facing lots of issues lately with my Fabia. Whenever I receive my car from the Skoda service, soon after, I see many lights glowing on my dash (definitely, an issue from the dealer end.) I'm no car geek, so please bare with me :3

So recently, I had my Fabia serviced for Engine oil leakage, clutch change, battery change. The car went smooth for 2 days and soon after, I saw a light glowing, I went through the manual, it was the Control System for Exhaust. I took my car again to the service center, they told me that my car's intake manifold isn't getting power. After a day later, they said the motor is not working anymore. Honestly, I feel like they've done something while replacing the oil filter which is located at bottom.

They charged me about 500 USD for the part but I wanted to drive the car once and I didn't feel any difference in acceleration. It was as it is, so I denied to change the part and wanted to study about this intake manifold,so I'm here!

Firstly, they've told me that, not fucntioning of intake manifold, will decrease the acceleration. But I found no difference, it was smooth as it was before. Could it be a sensor malfunction? And also can I also go for a good long drive on a motorway without facing a breakdown?

Any alternative ways to fix this? Or know whether the motor is working fine?

The service centers here are not at all reliable, so I'm depending on you guys!

Thanks guys!