During OLCI it shouldn't have any paid offers to upgrade as if U class opens up, you should be able to click a link to upgrade for free. This becomes a bit more difficult at the gate- but if outside the OLCI window, I'd either move to the front of the line, or find another agent who can push thru the upgrade. In the past, paid upgrades meant that U space was open, and one should be able to clear into it.