Rotting milk

I bought milk on Monday the 23rd January at picknpay Daveyton Mall, later in the evening when making coffee I noticed the milk is off , I then sent a DM to their twitter account with pictures of the milk ,my slip and my coffee showing lumps that the milk is not good. I recieved this ref number *** , they said the branch manager will contact me , to this day I'm still waiting, I've been texting then trying to find out whats going on but I keep getting the same apology that someone will get back to me. The worst part of all is that I kept the rotting milk in the fridge in case I'm required to bring it to the store. A week is a long time picknpay I'm really disappointed in your service, please do the right thing.