What can i do If they Lied about the cars mileage is it considerd fraud ?

I recently purchas a 2006 Infiniti M35 i have about a week with the car however when i bought the car they told me the car had 90,000k miles the contract said the same mileage and just yesterday i ran a carfax report and the car has had 2 previous owners the original and the dealer and now myself and it shows that when the car was auction it was reported to have 186,771k miles on the car i feel like they might have changed the odometer to make it a quick sale What can i do should i get a hold of a layer and see what they can do or if someone has experienced something similar what have you done?