Tajh

I've been stuck on the "big heist" mission for a week now I've looked up everything on how to get the email from Lester I've went to the marked areas but the cars weren't there i bought the cars and upgrades them myself but that didn't work I stole random cars but that didn't work I deleted the game (not the saved data) and reinstalled it but that didn't work neither I don't know what else to do now somebody help me