A funny thing happened this morning and before I book my 10 remaining flights this year I need some clarification. Flew DXB-IAD-LGA-IAH. At least this was supposed to be our return itinerary. 3 people flew - I am United Gold, friend United Silver and her daughter no status. DXB-IAD went smoothly. Even made it through customs in time. IAD-LGA was where problems started. Boarded plane taxied to runway then were informed no landings at LGA. So we sat for approx 45 minutes then returned to gate. We quickly realized there was no way to make our connection so once off plane tried to rebook. After 14 hours in air, we were still polite until it became apparent there was an issue with getting another flight booked. My friend had paid for economy plus for herself and her daughter. Even after being shown a receipt on United's website for the upgrade purchase, customer service advised that they could not book them in Economy plus because they could have gotten those seats by Economy being full. Not sure what this had to do with receipt. They then gave me my boarding pass in 35B. I advised them that I was Gold and would like a seat in Economy +. I was advised that I was on the upgrade list??? What?? I then requested an aisle seat and was told I was on upgrade list??? My friend had a middle seat in economy but her daughter with no status had an aisle seat. We then took boarding passes and headed for a supervisor. This is where my question is. We all got aisle seats on the flights we found, but I looked at the upgrade list and I was number 12 ( no I was not surprised), but my friend (United Silver). Was number 2. I asked the supervisor what was going on and the answer shocked me. She replied " the silver must have purchased a different fare class. Anytime a silver purchases a higher fare class than Gold, they will be higher on upgrade list than Gold." What??? So if I pay more regardless of status I will move up list?