Renault megane cc vvt 2lt Brake crunch and ABS light issue!!!!

Hey everyone

I'm new on here today so bear with me if I make errors.



I've just brought the following car.

2004 Renault Megane cc vvt 2.0 manual.

The car has been absolutely fine but recently noticed when I brake, intermittently I feel a slight shudder/crunching through the brake pedal.

At the same time, every now and then the ABS, service & STOP light comes on.

This goes off once I restart the car.



I've had a garage look at it, the garage I got it from; and they have so far replaced the ABS sensors, but the problem is still there......



Has anyone got any ideas what it could be! The car is in pristine condition inside and out so I'd love to get this issue resolved.



Any feedback would be appreciated.



Thanks



Jack