Confused: How does one upgrade from SLED 12 to SLED 15?

Due to some tech difficulties I'm needing to upgrade from SLED 12 SP3 to SLED 15.

[I've already done that part so that my computers are running SLED15 -- that's not the problem -- Just wanna make sure one understands I see this as an SCC problem.]

The SCC system doesn't seem to have a way to get a computer upgraded. There isn't a specific path to get from one level of SLED (in my case) to another within SCC.

I have not found a way to do this -- apparently using the assigned registration codes for the two physical machines I have doesn't actually accomplish this.

I found this out on Sat Nite when I went to put on maintenance and started getting messages about logging on to repositories

So, what am I missing?

I don't want to go back to the "60" day trial registration code for both of those systems, but what choice do I have?

If one has to pay a new subscription fee, how about being real clear and upfront about it and say so? Give me a DO SOMETHING button so I can make something like this happen.