I have a 2015 with 60K on it which ran perfectly.

Just had it into he shop to have the @RevMax valve body, torque converter and bypass added.

Shop said it will not shift out of 4th- tried a new solenoid but still nothing.

Revmax said I need new tranny- BUT never ever had a problem with any gear or slipping before I brought it in for the upgrades.

How do I handle this?