I sure hope you can solve this problem! I've been near it myself.
What I did was to take my veh8icle to an auto parts store that offered a free analysis of the problem. You can then compare that analysis to the list of services on your reciept from the repair shop. If it comes up that the things the computer say don't work properly are the same things they said they fixed for you, you can then go to the better business bureau and the local attorney general and go after the shop for fraud.
In future, get this checked BEFORE you put your vehicle in the shop, so you can be sure to get ther right stuff fixed. Some shops will fraudulently "repair" things the never did need repaired. Another way you can pretect yourself from big bills is to call several shops and ask what they charge for the repairs recommended in the free analysis.
If you are curious, I had an analysis say that I needed to replace three oxygen sensors. Hubby shopped around for them, and he replaced them himself. He unplugged a whatzit that forced the onboard computer to reset, with the repairs already done. But I had an extra little benefit, a promise from the little used-car dealership where I bought my van, that they would do a free check and possibly make a minor repair. So, I took my vehicle back and got their check-up, too. Then I got it inspected and passed. Sounds great, right? Alas, about a month later, the van was totaled. Frustrating!!! Fortunately, my son had a second car he was going to have to sell anyway.