it is a 125 cc ungeared scooter avl in India?does such a small bike require disc brakes and don‘t they require more maintenance?
He did not replace your oxygen sensors, one is bad or all
You're going to need to get the computer scanned to see exactly what the fault code is that is tripping the check engine light. It's too bad that you've spend that money and it hasn't rectified the problem. I would advise you to go back to them and give them a second chance to repair it properly. After all, you've already paid them a lot of money.
Based on 42 years of driving experience, as far as efficiency is concerned, it doesn't matter. The brakes stop the tires and the tires stop the vehicle. The 1968 Plymouth Road Runner (USA) had 11X3 drums in the front and 11X2.5 in the rear and I never faded them even with hard stops from 140 mph. OTOH, I faded a disk /drum brake set on a 72 CB-450 Honda bike from 90 mph. Buy what you're comfortable with or can afford. Budd
