tire, check engine

I had been going here for over a year and I thought I was getting great service, when in fact I was not. They gave me a "great" deal on a used tire that went flat two days later. Had to call AAA who told me that the tire was so bald it should have been illegal to sell to me. Juan charged me almost $70 for that used tire. Then the check engine light came on, was told by Juan that it would cost over $1000 to fix. Felt i needed a second opinion after the tire incident and was told by new shop that the engine light misfire was due to the wrong type of spark plugs put in. Jordans had put in these spark plugs 6 months previously. They do not do quality work, especially on my foreign car (saab). I feel like they took advantage of me as a female with limited car knowledge. overcharged me and did not even fix my car problems but created new ones. my advise...use a different foreign car mechanic.