AC1200 Duel Band Extender Help/Question

Just a n00b trying to get faster Internet/Refresh speed...

Hi!

I purchased a  AC1200 Duel Band Extender, I've set it all up, all the lights are solid green (this is a good sign apparently :smileytongue:)

The issue is.... it has not helped my Mbps at all!? have I done something wrong?
anything I should check or try before i get very annoyed with the $200 I spent on this this? (Price of this item in Australia)