OK.. get a turbo lighter .cigarette lighter.. put some heat the the exposed axles shaft.. not alot this should help.. sounds like u spun the 12mm hex to the plastic wheel.

see if u can see the 12mm wheel hex on the axle..see if it has ground its way into the wheel..sounds like this is ur issue..

a more drastic removal may be required.. side cutters and a dremel tool..
Ugh Buwannah..zug zug LOL..