1998 Ford Explorer Air shock Suspension

We took our 1998 limited ed to mech. For tune up. They completed the tune up and we picked the car up, they told us the Air shock Suspension would need to re-set
( not sure why) should take about a day and half. When driving the rear shocks don't work at all. The car rear bounces all around when you hit any little bump, it has been 2 days. Looking take back to the shop to see what is going on. Before the tune up the car suspension was fine.