Already paid to download os x lion and my computer needs another upgrade and apple store doesn't want to reinburst the money i paid.

Already purchase os x lion sofware to install on my computer , but gave message that it needs anothers upgrade as core 2 Duo, core 13, core 15 and core 17 OR Xeon Proceos to install OS XLion. I have Snow Leopard 10.6.8 2GHz intel core Duoo. Memory 2GB 667 MHZ DDR2. the point is that apple store doesn't want to reinburst the money i paid. Any of U have a suggestion, please?