It can be hard to tell what's wrong with your transmission until a mechanic comes along and sees what's going on. While this requires you to get to the hard parts, it will still save you money if you figure out that the problem is as simple as a belt slipping and there's nothing wrong with the gears.
You can see how easy it is for the mechanic to trick you and tell you that the entire module needs replacement when all you need to do is fix the gear the band is made of. That's why it's so important to choose your mechanic wisely. You can search for a reliable mechanic to perform general auto repair via https://frankstransmissionsautorepair.com/manual-transmission-repair/.
It is easy for them to make a little extra money on you by misdiagnosing your problem on purpose. Because of this, you might even want to have a second opinion if you have the time. It might help to question your mechanic and ask specifically if it could be a problem with the bands slipping. Putting them on the spot in this way might make them choose to be honest with you since you showed some knowledge about your car. If your mechanic has been trustworthy in the past then you probably have no reason for concern.
If you end up needing a transmission repair instead of a replacement, consider yourself lucky. Now that you know more about how this part of your car works, you may be able to diagnose the problem. We hope you never get to the point where you need a new one. If your car turns out to be in need of more than just a gearbox repair, you can take a positive view and realize that you may not have to worry about replacing that part again while you own it and are driving it.