Chrysler Sebring Cabriolet 2010
 

I have had my Sebring since new, now suddenly stuck in 3rd gear - anyone else had this happen and if so how to solve??

Sounds like you may have a speed sensor issue. The Powertrain Control Module (PCM) uses two speed sensors, one to measure input RPM and one to measure output RPM. These inputs are essential for proper transmission operation. If they fail, it can cause the transmission to go into "limp mode" where it stays in one gear to "protect itself" from further damage.

I'm assuming there is a check engine light or other fault code. Get the codes read from your dealer or other facility to verify what faults are stored.

Good luck on resolving this issue asap!