We're sorry for the inconvenience this has caused you.
The "transaction limit reached" is a notification by the Shell app letting you know that you have reached the allowable attempt to purchase in a day. May the attempt be successful or failed it would count on your daily allowable limit. Once limit has been reached, you will be able to transact again to any Shell stations after 24 hours from your last attempt.
What are my other payment options?
As an alternative, you may pay using your credit/debit card at the pump or pre-pay using cash inside the convenience store.