Bro...mistake already made. No point crying over spilt milk. See whether they will refund you the money for returned goods. Normally if it is bubble pack, the retailer won't take it back. Then the next step is to engage CASE to pursue the matter on your behalf. If you are not member of CASE then you got to pay a membership fee.
For info: Vitacon is made for video cameras. The lens due to its lower optic quality will degrade DSLR images.
How come your name can change?
Retail purchases return policy are governed by store policy usually... do you think such a store would have a return policy?
It's really tough luck for you, but there's little you can do. That salesman must've been really convincing to make you part with so much money so readily.
Do you normally buy things (eg. furniture, electronics, car, property, etc) without checking the market price?
I guess.. as a beginner in a certain hobby or business we all get conned sooner or later. Just discovered some similar adapter in the depths of my equipment storage box. I hope I will never find the receipt .. forgetting is a blessing at times
TS: move on .. it was a darn expensive lesson you booked here.