Frank Ross Pharmacy (NRS) - Received spoil medicine with broken seal

I am a doctor at Department of Pediatrics NRS Medical College Kolkata. I had visited their store namely the Frank Ross Pharmacy (NRS) on */*/** at around *.** am and had bought * packs of Fiberlact Granules ** gm and * strip of Pink total. The bill is attached herewith ( Invoice: ****-*-I********). One of the Fiberlact Granules bottles did not have any of their store label attached on it and when I reached home I was shocked to see that the seal was already broken and the medicine inside had already changed its colour. I went back to their store on Tuesday with all the medicines and bill but I was not given any replacement medicine for the spoiled Fiberlact Granules bottle. Instead, their store manager said that as there is no label this is not the product of this store. If that is so why was the medicine given to me in the first place for Rs ***.**?
Being a regular customer of their store I am really shocked how a doctor like me has to undergo such harassment. I urge you to look into this matter urgently and revert back to me at the earliest.