I'll give the dealer a fair chance of sorting it out (this email and up to one more chasing email next week), then if I don't get anywhere I'll contact Suzuki directly. I have some other feedback I could provide about how this stealership handled the process of selling me the bike in the first place anyway, if it comes to that!
Still, fingers crossed it'll all go smoothly... if this dealer does handle the claim efficiently it'll be a bonus as they're just down the road from me for taking the bike in to replace the bars. If, as seems likely, it turns out it was their fault for fitting them incorrectly in the first place, maybe they'll take a bit more care in fitting the replacements!!