A little more information on the symptoms would be helpful.  In general
if the fault keeps repeating every year its likely the dealer has not
repaired the main issue.

A basic service is all these cars normally need, oil and filters every
6K , plugs maybe 20K, leads maybe 50K, and so on.  I don't see what the
dealer is doing for $700, but in the UK they are not really suitable for
servicing older cars.  They are not really diagnostic technicians and
you are definately better off with an aftermarket specialist, possibly
combined with experts here.

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TonyS