Sour milk from Checkers (Moreleta Park Store)

I need to escalate the poor customer support by checkers. I found milk from bought from Checkers Moreleta Park store is likely to be sour or will go bad very soon after it has been bought. In the past I took the loss and did not reported the issue, but the last time I bought milk and it went sour I reported the incident to the store manager. The only thing he could do was to take my details with a promise that someone will call me. That obviously did not happen and I reported the incident on their web site - needless to say NO RESPONSE. My experience about customer service when a complaint is leveled is absolutely POOR.