Checkers Sixty/60? Never again.

I used the Checkers 60/60 app the first time without any issues. However, the second time, they reserved the amount on my bank account and then cancelled the order. Granted, they did cancel the freeze on my money, but it took two days. How was I supposed to buy food in the meantime? I further see on my bank account that the first order's amount debited was far more than what the checkout amount was. According to Checkers 60/60, they reserve 15% extra on your account for possible alternatives when certain products are not available, but I received no alternatives. I do not understand how their system works, but I do feel taken advantage of. I will definitely not make use of this service again.