Cheating and fraud done by a local restaurant and bar

Sir A local restaurant and bar sold me some promotional gift voucher & certificates for Rs.1,000/- which he promised to give benefits upto Rs.3000-4000. It had Gift certificates which entitled me a discount of Rs.500/- for minimum billing of Rs.1000/- or more and likewise a Rs.200/- GC which entitled me a discount of Rs.200/- for a minimum billing of Rs.700/-. At the time of purchasing this deal, the name of the Restaurant was ABC but we were told at the time of sale of this deal that the name would soon be changed to XYZ and confirmed that the said deal would remain valid for a year, in XYZ also. I used one the certificate the very next month and was honoured by which time the name was still ABC. After a few month the name got changed and when I tried to use my other certificate, the same was not accepted indicating the reason that the said GC's were sold by the old Restaurant i.e. ABC though the Owner, The parent company, the TIN No. ST No. all are same. What shall I do??? Pls suggest