1998 Chrysler Sebring Turn Signal Lever Right hand side of

My turn signal lever is broken with the left turn signal stuck in the on position regardless of the position of the turn signal lever. I have found a replacement part but my mechanic has informed me that the whole box assembly behind the steering wheel has to be replaced. However, the only thing not functioning is the turn signal. The headlights still function on the same lever. Is it possible to just replace that lever or is my mechanic correct? Also if I do get the replacement part how difficult is it to replace on my own or should I have a different mechanic do the work. My main concern is how to disassemble the lever/steering column and the saftey of the air bag.