Have you checked with Asus support if they can point you in the direction of whoever sells spare parts in your area? I know I can order stuff like this from a company in Sweden.
Your C: is probably a msata ssd which is located in a special slot on the motherboard.
Asus ROG G55VW:
CPU: i7 3630QM
GFX: Geforce GTX660M with 2GB ram
RAM: 2x8Gb 2133MHz Kingston HyperX Impact (surprisingly the G55VW uses the 2133 X.M.P. profile)
Storage: RAID0 with 2x 256Gb Crucial SSDs (both msata, one in a sata adapter)
OS: Windows 10 x64