My company only allows Y class travel and is very strict on the rule. I am about to book a ticket on a route where the Y fare is only $20 less than the C fare and was wondering if I would be able to buy up to the C fare from united directly once the tickets are issued. I would rather not get a refund and buy the new ticket in C, i just want to give them the extra $20 and get the C fare... I know you can buy up from a W to an H fare for instance when you want to upgrade with miles, I am just not sure about Y to C since it is a physically different class instead of a logically different class? Anyway, does anyone have any experience with this?

Thanks.