Bad online experience with rewards app

As I make use of Wimpy quite often, I decided to join the rewards program and downloaded the application a week or so ago. I earned rewards on two transactions, but had issues with the third. We went for breakfast at Meyersdal Wimpy last Saturday. I paid by Credit card and wanted to scan in the code on the slip to earn rewards when I got home, but got an error message that the slip has expired!! First time I got that. I send an e-mail (using the link ON THE APPLICATION) - only to get a message back that the e-mail has been rejected due to security issues on the recipient's side!! Phoned helpline this morning - only then I was told that I have only 1 and a half hour to scan the code on the slip and earn rewards - did not see this anywhere else on the application (not sure if that is mentioned somewhere in the fine print, but I did not pick that up anywhere). Quite disappointing experience and not very user-friendly application.application.