Amul / Gcmmf — amul shakti milk 500 ml

I bought amul milk 500ml from local vendor on 6th may @10pm. And put that into fridge. Milk bag clearly state that use by date 7th may 2018.
On the morning of 7th, i put the milk over heating and its just converted it into small particles and water came out from milk. Repeatedly i faced this kind of situation almost 4 times. And i cannot afford that much money to just waste everyday. I click the pictures and show it to vendor from i bought milk. He just told me to wrote a complaint and give him, that will take long time to proceed. Advise me what is the solution for us.