2006 ford escape transmission

2 weeks ago i felt a sort of jump in the car. it would go into 2nd gear but it wouldn’t go into 3rd right away. Since my foot is on the gas it was just reving up my engine for a couple seconds it took to jump into 3rd. I called my normal mechanic and set up an appointment for the next morning. i never made it there cause my car stopped before i got there. while stopped at a red light, then turns green and while i try to go, my car wouldn’t move. got it towed and was told by my mechanic that my transmission was shot. i paid almost $2800 bucks to repair it. last night my car started doing the same thing on the way home from work. I called my mechanic as soon as i got home and set up an appointment for the next morning as i couldn’t get it to them that night before they closed. i took it in the next morning and they test drove it and set it up to there scanner and they said it drove fine and that they got no negative reading on the scanner. i told them something is not right. they told me just to drive until it happens again as the transmission is still under warranty. i cant be the only one with this problem and i am wondering what is the real problem and how do i fix it? can anyone help please?