Terrible services!

I purchased a 400gram two in one coffee which has cremora in it! I opened the time had a cup and the next day I decided to mix my coffee from the underneath only to find GLASS in it! I laid a complaint to nestle about this , had a consultant by the name of Milly who was rude to me and says the factory insist it was coffee granules! What nonsense we are not uneducated that we can't tell the difference. So I asked for her manager to speak to me which is now past 3 days and no one got back to me! I am not letting this go as it could have being a elderly person who wouldn't have noticed this and could have lost they life's! Terrible and disappointing! I mean its R50 a tin which we pay for a 400 gram to enjoy!