SUCCESS!!
Called 866-264-1282 and they upgraded my plan which took less than two minutes. The lady knew exactly what I was talking about when I stated I wanted a "Sero Premium Plan."
Was then referred to telesales at 888-882-4030. Called and was on hold for less than 30 seconds. Took 24 minutes to get a Samsung Epic ordered. The system correctly reflected my new plan amounts and I will be receiving my new Epic by Thursday of next week.
I was eligible for upgrade so I received the full discount and my total after tax and shipping was $406 (and I'm eligible for the $100 rebate).
Also, she mentioned my account was eligible for 10 additional lines. I probed a little further and these lines would not be at the SERO Premium price but at the standard EPRP prices