Poor service

Very poor service from pick n pay. The service I receive from the guys who fill my tank is awesome, however from the store service is very poor. It's after 9pm I have my family in the vehicle and I go to make a purchase only to go home and open a litre of spoilt milk to add to my 3 year old boy's tantrum for his bed time nesquik. So I drive back to the garage to exchange it only to receive poor service! I opened 3 cartons of milk which was spoilt and finally got one that was fine. I was refused to be reimbursed on the milk as there was no cash or offered anything else at least to that value; It's not that I needed it but it's basic customer service, as a service provider customer service is top priority I was asked to come in tomorrow maybe.