Bought a 9 months old 69 plate A class sport executive with 3500 miles on the clock. Irrespective of the speed I’m doing the car can suddenly jolt like I’ve braked suddenly or changed down gear at speed then carries on as normal. If I’m doing around 70mph the car veers to the side. I can be on a straight bit of road, no other traffic near and obeying the speed limit. It’s scary. Due to covid Merc can’t look at the car for weeks. I contacted the rescue service who did a diagnostic but showed nothing. In desperation I just took it to Merc. The speed limiter and lane management were switched off by the mechanic who thought that might be responsible but it’s still happening. My 4th Merc and never had a problem before. Can anyone suggest what might be causing this?