How to deal with Notice under Section 138 of N.I. Act for stop payment

I have booked a caterer for my wedding reception for 220 plates. On the actual day hardly 180 guests turned out. But the the caterer could not return 40 plates of remaining food. It was clear that the caterer did not cook food for 220 people. The caterer has also manipulated the original menu as per contract and there were many missing items. Later I have also been told by many guests that the caterer was hasitating to provide costly food items (like mutton, fish etc) to most of the guests. A cheque of Rs.15,000 was handed over to the caterer just after the event when I was not aware of the mismanagement, dishonest and unprofessionalism of the caterer. Later when I came to know about all these from my family members and other guests, I decided to stop payment of the cheque. Now the caterer has sent a notice under sec 138 of NI act through his lawyer to pay the cheque amount of Rs.15,000 within 15 days of receipt of the notice. What should I do now? How do I prove the case in court?