phone card

Mac's Milk, on 3350 Fairview St. in Burlington across from Ultramart, Between Guelph line and Walker's line. I bought a phone card at this location. I scratched pin # and dialed access # .I entered the pin # and it said no minutes available and card was void. I went back to the location with a receipt and the store clerk lady refused to give me a refund or replacement. The store clerk verbally insulted me and told me I was trying a scam trying to return a used up phone card. As a former frequent customer of this location I have seen this same clerk get into arguements with customers in the past involving different issues.