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It's always easy to be wise after the event, but is the garage that checked your car a Saab dealer or Saab specialist? If not they will not necessarily been able to read the error codes stored in the engine control memory.
A dealer or specialist should be able to read the codes at a cost of around £50 or so, maybe less at an independent specialist. It usually works out cheaper to pay this, rather than have a general mechanic who is not familiar with Saabs changing random items and hoping to cure the problem.
There is also the situation that even if a fault is cured, the error codes may need to be cleared, or the car will still think that there's a fault.
If you tell us where you are based someone may be able to recommend a local specialist.