How to fix if only shifts to first and second?

Hello, for that estimate, you would need 'general diagnostics' first. As silly as it sounds, this may not even be caused by the transmission. If you have other questions, or need more information, let me know, otherwise, here is a list of certified shops in your area with the training to repair your vehicle: http://repairpal.com/pontiac-within-10-miles-of-marion-virginia-24354