It sounds as if the dealer itself may be the real problem.
What are these front and rear filters that got replaced? Fuel filters?
Is your car out of warranty?
Have you been paying for any of these repairs?
What codes are you getting?
It sounds like you might have an evap problem.
Get with the service manager at that dealer and tell him you’re losing confidence in their ability to repair this problem.
Have you been a lucrative customer to that place? If so, tell him they’re going to lose you as a customer if they don’t get this handled ASAP. The prospect of losing a “cashcow” may motivate them to put their best guy on it.
Can you apply the lemon law? Has it been there enough times unsuccessfully for the same problem?
Just a bunch of ideas . . .