Q: Unable to control steering when cornering

I was driving my Mercedes E200k avantgarde year 2007 model yesterday when while cornering on highway, the car swerved to both left & right, it appeared as if the front tyres not responding to the steering. Happened on again few minutes later on another corner and while turning at intersection. While this incident happened, a Hazard signal appeared on both occasion (the triangle with exclamation mark). Luckily no cars nearby early morning,it could have turned spinning.

Brought the car immediately for diagnostic check, the mechanic said from the scan it shows faulty on the ABS module and require replacement, which is very costly.

My question, why is the ABS sign never appeared while the incident occured, instead only Hazard dangerous sign appeared? Is the ABS module require replacement after certain mileage? Mine is 120000km. I dont feel safe at all driving the car if it is not fixed anyway, so I just heed what the mechanic told me so. What other option are there? Thank you

My car has 120000 miles.
My car has an automatic transmission.