Happened to me before close to 10 years ago. I called the bank and they told me that it was not uncommon for some gas stations do that. Then the operator proceeded to tell me a story about a family that took a road trip from NY to FL and hit up the gas station around 5 times. Each time they put a $150 hold. The family arrived to Florida with almost a $1000 short b/c you have to count that amount of money they spent on gas + the 750$ that was being held. I never went back to using debit cards after that.