WoW,without any research for the seller and they confirmed that 3 monitor works for it eh?
Seriously,it wasn't the buyer's fault.
If everyone doesn't know about comp then go buy from that shop,and just the SO called "Technician" say ah the rig can support 3 monitor
Then everybody will get ripped.

Anyways to be safe side next time have to double check the information before buying :S,that's what my parents always told me haha