Domino's Pizza — quality of pizza that leads to infection

Address:

Bangalore, Karnataka

My wife and son had non-veg loaded pizza in phoneix mall domino's bangalore on 24th of august. After the pizza which was smelling and bitter in test. My son got food infection and suffered for 4 days. When given feedback on domino's they are saying they will refund amount. I have asked for ingredients used that day and it's expiry date so that i can be assured it's not their fault. I have asked to settle doctor bill which they have refused. What is the lagal action we can take here? I am reachable at [protected] and [protected]@gmail.com.