Maruti Suzuki India — While servicing of my Suzuki access 125, a much expensive part about 6000 rs part not working

I was reported my Suzuki access 125 scooter for servicing, whatever they asked to change for better performance, I agreed.

But while delivery a new part called ecm of 6000 rs cost which was absolutely fine and working is now not working.

I have complained about the issue but they do not help and asked for 6000 rs for changing that part.

It means they have delivered the scooter with new problem.

Service provider is vaibhav Suzuki, ghaziabad