Sorry if I mis-typed. I didn't mean to infer they are going to purchase me an "upgrade", but that my ticket would be upgraded (refared) to a C on the return, thus retaining the initial value toward the return portion. Not positive that's what they're doing, or if they can, but it's my suspicion, as they wouldn't be able to access the residual fare amount any other way, and that would be a very financially poor way of handling the situation.

Since I would then be on a paid C fare, the SWU wouldn't be a double upgrade. It would simply be upgrading the C fare.

Hope that makes more sense. I wasn't clear enough earlier.