Just a few thoughts..
What attracts you to working for Debenhams?
When you are in the shop as a customer you've been impressed with the level of customer care, and the obvious team spirit and you want to be part of that.
Or she could be honest and say the money is good and the hours work well around her studies.
What skills and qualities would you bring to Debenhams?
Enthusiasm, willing to work hard, good team player (find example, netball team, after school club etc) Knowledge of fashion?
What does the term 'good customer service' mean to you?
Anticipating the customers needs, without being pushy. Willing to go that little bit further to help a customer, whilst being aware of business needs and limitations. Happy and enthusiastic,
TBH I hated reading applications from school kids for weekend jobs, as most of them put no effort in at all. If any of them bothered filling in those bits, or even putting a bit of thought into it they were immediately in for an interview Just remember first impressions count, so nice legible handwriting, good spelling, no coffee cup marks!
HTH, but I'm sure someone more qualified will have xposted with me by now!