eBucks and Double up rewards - Beware extra conditions not stated

What FNB and eBucks don't tell you: When trying to earn on the Double up fuel rewards, you are required to keep ALL receipts of every single transaction done on your qualifying cards. This is because they will take any transaction and use it as a non fuel purchase, this disqualifies you from the Double up rewards..... The only way to rectify this is to produce a receipt of the purchase. My specific case, they used a transaction made at a Motor Dealership for a service as a non fuel purchase. Luckily this is a large company and I hope I'll be able to get a receipt. Their terms and conditions only state to keep the fuel purchase receipts..