Defect on goods

I bought 6 pack yoghurt and 1 piece was missing factory fault. Wrote an email to parmalat. They requested a till slip ( perishable goods) gave them all the info they request, that was on the 19th April. I was told its been escalated even sent proof of a picture. Was told il be answered in 48 hours. Already sent two more emails for follow up. Nothing from their side.