Unconsumable product

I purchased C***** 1Litre 6 pack milk from pick n pay at Carlton center Johannesburg CBD and I found that it was spoiled and when I checked the expiring date it was not yet expired. I opened about 4 cartons and 3 of them were spoiled so I called C***** and they gave me R60 voucher. How can they expect me to accept such *******. I'm very disappointed in c***** and their services really to loyal customers.