No beef patty

Went to greenstone drive thru and upon ordering a BBQ Double buger meal i was give 1 with a single miraculousl I then queried with the gentle who was giving me my food and he confirmed that there was only 1and gave it back to him. I moved from the drive thru to walk in and miraculously there 2 beef patty in my burger. I then requested manager on duty, who was utterly and equally useless who brushed me off.