Petro Canada review: short changing the customer

After purchasing gas, I decided to purchase a Lotto 649 lottery ticket for $ 2.00. I gave the attendant my Petro Canada card and a $10.00 bill. He ran my card through the machine, printed the lottery ticket and gave me back my points card, lottery ticket receipt and $3.00 change. I told him that the change was wrong and he owed me $5:00 more while holding the $3.00 change he gave me. He printed the invoice as $5.00 & showing the lottery ticket $2.00 and $3.00 change.
He asked me if I was sure I gave him $10.00.

The same attendent did this same thing to me several months ago. I wonder how many other people he swindled out of their change.