I have a cracked 19" Champion RG5 wheel and i want to know if its repairable or not. Any advice on who to call?

 

I'd never trust the welded area not to fracture again. Welding would break the homogenous temper of the rim material; which in this case is probably forged aluminum. A forged wheel is rather like a bell, as I see it; one crack and the tune is forever changed for the worse. You can contact the manufacturer and query them for additional input. Time for a replacement to play it safe.