The issue has been solved. It was a loose coupler. It was under warranty and hence the bill amount was zero.
BUT, Fortune Motors has started charging Rs. 120/- for job card entry! That's a little hard to digest. My car is in warranty and it has an issue. So, ideally I should not be paying anything for it. It is their responsibility to make the job card, why should I pay for it?
Interestingly, on the job card, they write "Consumables = Rs. 120/-"!!! When I asked what consumables are being used for my car, they admitted that it is actually job card entry fees. This clearly indicates that it is malpractice, else why would they write 'consumables'? I dint make a big issue out of it as these guys are in very good terms with me & gives me excellent service & I did not want to fight with them for 120 bucks.