For clarification, which Disney phone line did you call to upgrade your 10 day base ticket (one park per day) to the 10 day hopper? Did they offer you the discount because they could see you had a qualifying DVC stay? When I tried to call Disney's "existing ticket" line, they could see I had a DVC reservation, but were not aware of the DVC promotion & were only able to apply 2 extra park days to cash hotel/theme park ticket packages.
I currently have a 7 day base ticket purchased last year when they were only selling 7 days max, no hoppers allowed. Now I want to upgrade to a 9 day hopper but I'm unsure which line to call because both DVC (called them on 1/5/21 & CM told me only a 4 day ticket could be upgraded to 6 days) & existing ticket CM denied me the DVC offer.