Hero Motocorp — ismart 110 engine problem

Address:

Aurangabad Maharashtra India

I have purchased hero ismart 110 in 2017 and till the date engine problem is not solved by any of your authorised service centre located in aurangabad. During my every regular service i have telling them the engine problem and they are doing something and taking money and bike doing smoothly for one or two month and problem and same problem occurs.
What should i do now???