TiredSoul

Take smaller steps.
Go from piston to turboprop to Jet.
When you get a class-date give yourself more time. You can find any airplane systems online.
Study before you go.
May even do a sim or two on your won dime before you go to class.
If you can find a sim with a couple of open slots.
I went from flying glass for 10 years to an analog jet. That was interesting too.

I think the first one is on you.
Shoulda coulda woulda prepare more prior to going to your first Regional.
But you’re not alone, lots of posts here from people that didn’t make it through their first Regional training.
You didn’t pass the ride the second time but you didn’t state why not.
Was this something skill related or decision making related ?

in addition to what I said before put some tar on your soul and consider that next time failure is not an option.
Study study study before you go.
Find somebody local or even on here that flies that airplane. Pick their brain over systems.
Teach yourself the airplane.
Have all company assigned groundschool finished before you go.
It makes for a lot less stressful first couple fo weeks or week in case of 135.
If you find your training partner to be the party type ask for somebody else.
Exercise during training as it gets rid of a lot of negative stress.
Come back from the school house take a power nap of 1-2 hrs. Then go study solo then with your training buddy.
The lesser the stress levels the better you will perform in the sim.
But treat it like astronaut training and you’re heading to Mars to save mankind.
Really.