Maruti discontinued Ritz to launch boxy Ignis

Hi All, my Ritz has clocked 112000km in Less than 5 years. Cheers to its ride quality , driving position and a superb high way mile muncher. Good for a family of 4 and a bit squeeze for 5 adults. Currently I started facing problem with gear shift from 2 to 3 and unable to understand if its a normal wear n tear or any serious issue. Showroom guy gave a big laundry list of items to be replaced while quoting 15k only for gear box over haul. BTW what is the reliability of this over haul and how sure are we that the same issue doesn’t crop up again. Also is it mandatory to replace timing chain if the car has crossed 100k kms. Can anyone pls suggest??