Saw your United post but it was locked down. Frontier will not do status match, under any circumstances, at least they didn't 2 years ago (I am GS at United).

Honestly I would consider buying the ticket and be done with it. The difference between the 150$ change fee and the new fares is at least for me not worth the headache of waiting at the airport all day long if you can't catch the morning flight

Frontier does have various ticket types and you might consider next time to buy up to a more expensive fare up front if you assume your plans might change.

https://www.frontierairlines.com/fro...rs-tutorial.do