Great jeep, terrible service, asked not to return.

We've bought our 2015 Jeep Cherokee limited new off the lot and it currently has 34,927 trouble free miles with the exception of the passage side cv axle shudder that was covered under warranty. Our only real issue with the car is the interior, specifically rear seat room. It starts getting small quick when you start putting car seats in the back. We liked the Jeep and where currently looking at the Grand Cherokee as a 2nd vehicle.

We where looking until today when we took our vehicle in for squealing tensioner that this model is known for when the temp get extremely cold.
I called the dealer spoke to service explain the issue gave them the TSB # 07-001-15 and said to replace it and asked if it would be covered under warranty or recall.
I got a call this morning stating the repair would cost $620.96. I was blown away and asked which why so much & what pulley was bad. She explained it was in a very difficult spot to replace, they had to R&R the coolant, replace the pulley, re- diagnosis it to make sure that was the only bad pulley and possibly replace another if it was making noise also. They couldn't tell me what pulley was bad.
I said no, it sounded irrational. I asked how much to replace the tensioner that I originally asked them to replace. I was told $335. Well that's still didn't sound right so I called jeep cares. While on the phone with jeep, jeep was also on the phone with the dealer who then quoted $280 to replace the tensioner.
At this point I had enough and nothing says shady like receiving 3 different quotes for the same repair.

I went to pick up the car and much to my surprise they where going to charge me $190.00 for diagnostic. I asked why, I wanted the tensioner changed and that wasn't done. He said that may not of fixed it and could possibly have to replace the idler. When I replied with "that's what you were going to do anyway, you couldn't tell me what pulley was bad and if you didn't replace the correct one you would charge me to replace another. If I wanted a new battery, you would replace it because that's what I paid for. Not run a $190 diagnostic on it".

It was at this point they where getting mad and responded with just take your vehicle and leave. They asked they I not return to there dealer.
I'm assuming the service manager wasn't aware I was going to by another vehicle or the owner knows the service manager is dictating who can come to there dealership.