Which clothes shop voucher for teenage girls?

[Scrunchcake]

I'm so out of touch with what teen girls are into, please give me some pointers if you're more clued up than I am!

My nieces (15 & 17) will be in the UK for Christmas this year, visiting from Australia. They live in a smallish town there with very limited shopping available. For Christmas they would like vouchers to do some clothes shopping while they're here. They'll be travelling round a bit so online shopping isn't really an option, or as much fun for them.

So which shop(s) should I buy vouchers for? They aren't strongly into any particular "look" - they're quite outdoorsy, casual and beachy but also quite like being dressed up and girly. Please help!

Top Shop or Urban Outfitters

My DD is 17yo and these have been her favourite Go-To shops for a couple of years .

What about a prepaid debit card? I know there's a small admin fee to set one up, but then they are free to spend whatever they like in any shop.

Think I'll look at Intu vouchers. Thanks everyone :)

If the girls want alternative things rather than mainstream then afflecks Palace in Manchester Northern Quarter may be the best place for them to start. There's other shops with similar items nearby such as cow and lots of quirky cafes for lunch. There is a really big primark a few streets away as well.
It'd have to be cash though

@Starisnotanumber Being from small town Far North Queensland, Primark is kind of alternative for them (not capital "A" Alternative obv) but thank you :)

I see where you are coming from. They would probably be better in the enormous primark There's no real primark store in Trafford Centre just a small area in selfridges so if that's the shop they want Trafford Centre would be out.
Northern Quarter good for lunch though and just people watching.

I was about to say cash is the most versatile voucher of all but your updates show that they really do want vouchers to release them from any feeling of guilt about not saving it! @Themountainsarecalling 's idea of a pre paid debit card is worth considering.