Up to 3 rewards can be redeemed in a single transaction, provided they are for different product groups. A fuel, sandwich, coffee reward/offer, for example, is fine. You can only redeem one fuel reward per transaction.
If you attempt to activate multiple fuel rewards, the reward which expires first will be redeemed. If the fuel rewards expire on the same day, the one of higher value will be redeemed.
Additionally, for customers that have connected their Uber account and get a % discount, please be aware that this benefit is only valid if it is the only fuel reward being redeemed in the transaction.