I actually really like a lot of their stuff as well, especially the homestuff and the designer ranges.
Does your store have concessions such as warehouse, oasis etc? Could you spend the vouchers there? (Sorry I don't know how old you are so don't know how appropriate this would be!)
Or what about spending it on any homestuff you need, duvet covers, crockery sets, la creuset, suitcases etc?
Does it have a beauty area? i find it's never too hard to spend the money there, on perfumes, makeup and beauty treatments in the beauty parlour!