Bingo. Retaliate with whatever music will drive the customers away, at a higher decibel level than the gas station can put out. If there are no ordinances to stop the gas station, then there are no ordinances to prevent retaliation, and the dispute must be settled by the law of the jungle.
Chances are that the TV’s on the pumps aren’t loud enough to warrant intervention. But if your sound can overwhelm their sound at the pump, you’ll be charged.
It’s no different from your elderly neighbor’s TV being heard outside.