$1200 for IC piping and to mount an IC? Fabricate a DP?

Did you have all the parts? if you did thats kinda steep.

If you had a BOLT ON KIT, an a DP fabbed i can see it being $400-500 (figure 2-3 hours for the IC kit to be put on, bumper trimmed, $200 for a DP)

If you had a universal kit, i can see it costing upwards for $700-1000 to have it fabbed an put on.

But you are right, they should have called you. Did you sign and estimate?

Usually they need to tell you an ESTIMATE up front, and if they go over that you call the customer.

EDIT: danny leave the shop bashing out of this . No need to start crap.

The OP needs to post more detailed info.