well perhaps you could ask them kindly to fix it, and if that does not work you could somehow file a complaint with the state. perhaps tell the state that they broke the exhaust and prove it by explaining that if the shop was any good that they would have failed the car instead of passing it if it had a bad leak when it came in.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual