Is there any way to prevent waitlisting for an eupgrade to Premium Economy?

When I re2uested the upgrade I saw boxes for PE and Business and I checked only the box for Business.

But I was upgraded to premium economy which was not at all what I wanted.
I went from a window seat in economy (with a possible empty seat next to me) to a middle seat (which I hate) in PE.

I thought that if I only checked the Business box in the upgrade process then I would not get upgraded to PE.
But according to the wiki above in fact checking the Business upgrade box also waitlists me for a PE upgrade.

Is there any way to stop that? I dont think it is worth spending the eupgrade credits for PE.

Thanks for your advice.