if it is showing 16gb ram it is probably right.

what they might mean is that each slot supports up to 8gb ram, so 2x 8gb

of what I can see the K55VM has HM76 Chipset which supports up to 32GB RAM

you can always check if it indeed has access to all memory by using more than 8GB RAM Disk fx 12gb of RAM Disk
and see if it can create it or fill it up 🙂

I know that the K55VJ can allocate all 16GB RAM 🙂 which has the same chipset.