Buy a noseband cheap off ebay, use a stanley knife to cut the buckle end off of the nosepart. Punch holes in the other end. viola extension
Try and buy one a similar size and type to the one you already have so the thickness of the leather and the buckles fits. watch if its a hunter one as the leather usually narrows down to the buckle end.
OR buy a thick flash strap and cut the end off it to shorten, punch holes where needed. Funtional but not as neat as first option.
Or get saddler to sew longer strap onto existing noseband, he can move the buckle if needed.
I've had to have saddler sew extra pieces onto noseband and throatlatch in the past. I've also had to buy an extra long browband. The bridle fitted Shire/Clydies.
Now I have a Westphalian Draft horse, her head is enormous but a completely different shape and the noseband is still abit tighter than I would like and the throatlatch is too long.
The local saddler is definitely the cheapest option though, IME.
I have a spare noseband that i bought for nancy (clydesdale) its extra full. If you are anywhere near worcester you can have it. It cost me 25 quid and is nice english leather, but as its xmas, its yours for nowt, inbox me if that would be any good to you?
I bought an XF noseband for my Clydie X and found that the strap with the buckle which goes over his head was too long and needed to sit up past his browband, under his head strap part, to sit the noseband in the correct place on his nose I didn't anticipate this when I bought it, what a numpty! I think I'm going to have to venture down the bespoke route......