calvert's express Messed up on a tune up and gave me the wrong DIAG for my car st charles, Missouri

 Monday September 26,2011 I arrived at the shop at about 12:30. I have been getting work done on my Caravan from this same shop on three other visits.  I kept coming back because, I felt I could trust this shop. I went in the shop request and oil change and and a tune up. I had asked about the transmission service.So I went across the street to Target,to do some shopping  I was called by Brandon , the manger on duty at the time. He then had stated that my fluid was clear ,I didn't need transmission service. He stated that that my wires were old and I could use the tuneup.. He quoted me the price, and I was unsure at first because of the price. So I told him I would call right back to confirm with my husband. I did and told him to go ahead with the work.. So the car is ready around 2:30 and I pay a total of $290.80 for this Tune up and oil change I was told. So As I go get in to my car, and start it up it it doesn't start up right, I felt as if the car was about to cut off. I then went back into the shop and told the lady at counter that the car is not running the way I t was when I brought it in. She get's Brandon and he say's wahts the problem. I tell him that the car is running very rough, and I don't think I will make it home. He tell me that the is because , My check engine light is on!! I said in response, I don't think so. My check engine light was on before I brought it into the shop, never once did you say anything about it being on are it causing my car to malfunction after a tuneup! He says well all I can do is run an diagnostic check on it.  I'm  hand over another 69.99 for you to see why my car is all of the sudden running extra rough.So He then tells me 2 hours later that I need an ECM module $934,00 to get it fixed. So I say are you sure, yes everything keeps going to computer is bad.Visit the shop on tue, and wed, trying to get them to look over the tuneup, there was an misfire, There was a bad spark plug,  needed an injector, not ECM went to another shop to get DIA done.