Fermentation temp when adding more yeast

Background: A few weeks back I brewed an ESB with WLP007. For some reason (unrelated to this question) it stalled around 1.020, and I was advised to pitch a pack of dry Nottingham yeast to get it closer to 1.012ish which is what I wanted.

The 1.020 sample was a little sweet but otherwise totally clean. Five days after adding the new yeast, I took another sample. It tastes like ASS I controlled the primary ferment temp closely, but when I added the new yeast the carboy was just in my hot-ass basement in the high 70's. I figured I was pitching a ton of yeast and it only had to drop 4-6 points so it wouldn't develop any flavor. Also thought the warm temp would encourage it to finish off that remaining sugar. Seems I was wrong.

What do you guys do about ferment temps when you need to pitch new yeast? Do you make sure to drop the beer back to the mid 60's before pitching again?

Wlp007 stalled? That surprises me, it usually goes well over 80% attenuation for me, like it or not!

And yeah, I think you know what you've got to do in future, especially with Nottingham. Does it have a lot of banana? And what is your gravity now?

Was it an extract batch? Oftentimes extract batches can 'stall' out at 1.020 but are actually done fermenting.