I booked a comfort fare to Curacao in April with a 20% discount code. I'm looking to up-fare to Latitude to be able to upgrade to Business/Premium Rouge. A couple of issues/questions:

1. I am waitlisted for an upgrade and the system won't let me cancel the upgrade request (which I need to do to change the flight, as I was trying to see if the discount would be there if I tried changing the booking to a latitude fare). This (being unable to cancel an upgrade request) has happened to me earlier this year as well. Is there a solution other than calling in?
2. If I call in, will the agent be able to process the change with the discount applying to the latitude fare?
3, If I have to cancel, I gather upthread that I can ask to have the discount code reactivated so I could then book again. Last post on this was three years ago - anyone have more recent experience?