Pep Boys ripoff Incompetentent mechanic or a liar Pepboy screwed my emssion test SAN DIEGO California

I brought my 98 Ford Taurus to Pep Boys at 4441 GENESEE AVE, SAN DIEGO, CA for a smog check (state emission test) on June 12, 2007 before selling it. The same smog test was performed on my taurus about 8 months ago for registration and it passed easily. Since my car is religiously maintained, I didnt expect any odds for this test. When pepboy staff told me my car failed with excessive HC and CO emission, and tried very hard to sell me their diagnosis service, I said no and pulled out my car. I immediately ran another smog test at a different shop and my car passed easily with a result consistent with its previous emission test. Below are the test results on HC and CO emission from pepboy and the other shop. Just let the fact speaks
Pepboys's report
speed HC (PPM) CO (%)
15MPH 75 0.50
25MPH 138 0.75
Another garage's report (I cant release its name according to the policy here)
Speed HC (PPM) CO (%)
15 MPH 36 0.24
25 MPH 28 0.31
Pepboys's reading is two times more than the report from another store!

Now, go figure, pepboys is either not competent enough to do a simple smog test correctly, or intentionally failed my car to sell me unnecessary service. In either situation, pepboy should be punished for their imcompetency and bad work ethic. I requested a refund of the test, but the service manager refused.
I will never go back to pepboy and will never waster a great deal of my time and money on their horrible service. Never, even for a simple smog test.

Qian
San Diego, California
U.S.A.