Vibration issue
No reason why you should have to waste more of your time or pay for their incompetence and poor customer service.
Variously it could be things like a problem with the driveshaft (my first instinct from your description), an out of round tire, an ignition issue, a torque converter issue, maybe a halfshaft issue, a bad engine mount, or a variety of other things.
hardly ever I defend the dealers or throw them under the bus either without having something that makes sense and they can be prove incompetent.
you need to give more specific details on your "big trouble" as you call it whatever it may be.
bad axles, bent wheels, out of round tires, broken bushings, bad torque converters, bad driveshafts, bad transmissions, bad coils, unbalanced flywheels and just about anything else that can make a drivetrain vibrate/shake/rattle or wooble have been driven by me on a very frequent basis and never had my feet "numb"
personally I think you may be having a hart attack, no dealer can help you there.
how can only the gas and brake pedal vibrate?, why would you have your feet at the gas and brake at the same time?
I hope that's not the case ....
I personally do not think that there are any more low class and deceiving people than dealers, especially service. But they will pay it one way or another....
Good luck








