I couldn't find a thread specifically around award booking changes, so I'll ask here.

I have a confirmed PEY ticket waitlisted for J. I noticed that seats on Qatar Airways became available on the same route (via DOH) -- how do I change my CX PEY ticket to a J ticket on Qatar? It doesn't seem like I can do it online. Does CX waive 'other channels' fees if they are unable to be done online?