ESP warning light

[scooters]

Hi all,
I need to pick your brains.

I've recently had the front brake pads and fluid changed on my a3 (2000 1.8T) and whenever I now brake with anything more than a gently foot, the Esp warning light comes on.

Turning the engine off and on again rectifies the issue..until you brake again.

Has anyone else had this issue or knows where to look?

many thanks for any suggestions