Which third time? Third broken spoke on an otherwise unaddressed problem? That's just the expression of the problem.

I think the first spokes to go are the spokes that were under the most stress. It isn't a random failure. So I think it possible that the other spokes are fine. 18-8 stainless is relatively plastic - if it isn't obviously damaged, it is probably fine. I have trued lots of wheels that had a history of broken spokes and the carnage stopped once the tensions were evened out and elbows seated. So that's what I think the OP should do if he wants to keep riding his bike until the warranty claim resolves itself.