Is this offer too good to be true?

I recently took my car for its first annual service to Arnold Clark who I believe are Scotland's largest multi-franchise dealer. All was in order, the cost being £240. On leaving I was offered the choice of a 2, 3 or 4 year service plan, the latter being quoted at £639 to include 3 MoT Test fees. The fee has to be paid at least 61 days prior to the next scheduled service date. To indicate the attractiveness of the offer the one-off price for the next (2nd) annual service was quoted as £416.45. It does seem a really good deal - I would be grateful for your comments.
Hyundai offers its own 3 year service plan.
Answered by Honest John on

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