Exhaust weld, TPS replacement

Terrible. Took my 99 Isuzu there because the exhaust system had loosened up and needed welding. Got talked into replacing the transmission pressure sensor as well to get rid of the error code. After work was done, the car would idle high and it started shifting hard, also the TPS error was still coming up. I took it back and asked them to fix it. A disgruntled mechanic told me he looked at it and couldn't do anything because the problem was electrical. Took the car to a friends relative who's a trustworthy mechanic. He informed me that they had installed the wrong TPS, which didn't align properly, and they had wired it wrong. It would go to about a 30% throttle at start up, then the voltage would actually decrease as you applied the gas pedal (it's supposed to gradually increase). Now it's been about 2 months, the exhaust weld has completely come undone and my car is loud again. The work they do here is horrible and I have no doubt they cut whatever corners they can. Do not take your car here it is a rip-off. Here are some more bad reviews: http://baltimore.citysearch.com/profile/603358552/cockeysville_md/meineke_car_care_center.html