Monroe Muffler Brake & Service Poor quality welding, multiple exhaust leaks, horrible customer service N. Charleston South Carolina

In November of 2008 I had Monroe install two catalytic converters and two rear tail pipes on my 1999 Chevrolet Corvette. The labor cost was $250, which seemed pretty steep for a simple cut and weld job. Keep in mind all the parts were provided, all they did was the cutting and welding. Upon arriving home I pulled into my garage and noticed a ticking/pulsing noise coming from under the vehicle. I immediately knew it was an exhaust leak so I turned around and headed back to Monroe.
Once I arrived back at the shop the manager assured me there was no leak and that since he did the work, it was done correct. After explaining to the manager once again he sent one of his employees out to my car who then verified there was indeed a leak. The manager agreed to fix the leak and within twenty minutes he had fixed it, or so I though.
I listened under the car once more and did not hear the leak. I assumed it was fixed and drove home only for it to start leaking again. Being frustrated and also having to go to work I decided to let it go and check back in the following day. Another problem that came up was my check engine light and after scanning my cars computer it showed an o2 sensor low voltage (lean) code. After calling around to my local shops and dealership they determined that air was somehow getting in the exhaust system before the catalytic converters.
The very next day I brought the car back to Monroe and was determined to find out why the exhaust kept leaking. The manager immediately starting giving me a bad attitude and again assured me that it wasn't his welds that were leaking. I basically told him the car was running fine before he touched it and is now throwing a code and has a pulsing leak. The manager finally got my car back on the lift and verified that there was a leak where his welds were. What he did next pushed me over the edge. Instead of fixing his leaking welds by welding them in, he used exhaust paste, which is a temporary fix and not something a reputable shop should use. At that moment I told him to scrape the paste off and weld it but he refused. I decided it was better to leave than to start an altercation and potentially get myself into trouble.
I got fed up dealing with Monroe and having my car not running right so I ordered a full exhaust system and installed it myself. Once i took off the stock system (Which Monroe had worked on) I noticed that the welds were not even complete. They were only welded on the bottom section and not on top. There was not a complete circle around the circumference of the pipes. The welder could not reach the top of the pipes so he just left them open up top.
I am very disappointed with Monroe's workmanship and customer service. I would not recommend them to anyone and I hope to get refunded for the poor quality work done to my car. I will post a link with pictures of my exhaust system and where the welds are open as soon as i get them uploaded.

Robert
Charleston, South Carolina
U.S.A.