It seems you are being taken advantage of by the mechanics you’re using. For one thing, you only need to drive less than 100 miles to reset the computer. 1000 miles is ridiculous, and implies that they are just trying to get you to waste enough time so you can no longer dispute the charges.
You need to know the OBD Trouble Code that your car's computer registers. You can read it with an OBD diagnostic tool such as the one I mention in my article. That’s the only way you can take control over the situation.
The trouble could be any number of things. Check the trouble code yourself and then get just that single item repaired or replaced.