Yes, take it to a better garage. You might have to go to the dealer as the places you have been using clearly dont have the correct diagnostics equipment. If some one has been messing about unplugging things all the fault codes will have to be deleted to get the light out.
Incidentally, if money is tight, just ignore it. The car will not fail an MOT with this light on and is legal to drive. However, if you are in a crash the airbag will not deploy.
hth
November 2009
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