Dineout — restaurant refuse discount. and dineout is giving only promocash as a service gesture

I booked table for 3 at zaika restaurant dadar east. As it was giving 15%discount.
When i visit the restaurant, the attendant refuse to give the discount as he said we don't have dineout partnership.
So i escalated at dineout support team. They are given me 120 as promocash which can be used only 20% and validity of 90days.
I have loss of almost rs.250