Diary milk - Spoiled chocolate

I've bought three dairy milk fruit and nut chocolate of rs. ** from the local store. But I've got a fully spoilt chocolate. The shopkeeper didnt respond well and he refuse to refund also. I only open the packet and got to know its totally spoilt, but what if my * year kid open it and eat. Who will take the responsibility if something happens to my child. All I wanted a explanation and little courtesy towards what happen. But shopkeeper is very rude to ignore this matter. And he didnt give supplier no. I really wanted to bring attention to cadbury and the supplier too... its a need of the time as every chocolate lover kid has right to be safe and healthy.