2 year + 1 year course PGWP

Hey everyone. So, i'll be completing my master's this march. I want to study a post grad diploma as well to specialize my field of study. The diploma is for a year.

Just wondering, what will happen to my PGWP? Will i get 3 years or just a year of it? Also, do i need a new study permit or just an extension?

Tried calling IRCC, no luck!