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If you took it into a store to be repaired, the cost for this is going to be near the cost of a new replacement one, plus you will only get a short warranty.
Your best bet in my experience is to try to locate a non working second hand flash which you can check on Ebayhttp://www.ebay.co.uk/bhp/canon-speedlite-580ex-ii
And if your handy, put your flash unit into this.
Or purchase a replacement. But taking it into a store will not be economically feasible in the long run.
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