I am an Army veteran and was just discharged in June 2015. I am currently attending a community college and have been using the Montgomery GI Bill benefit. Just recently the tuition went up, putting me in a financial hardship. So I have decided to switch to Post-9/11 GI Bill benefits. VA just informed me that I am not eligible to switch my benefits. They claim that if you choose the Montgomery GI Bill you are not allowed to switch your benefits to Post-9/11. Is this true?

If you have a single qualifying active-duty service period any time between Aug. 1, 2009 and July 31, 2011, you may be eligible to use that one period of active duty to qualify you for the Post-9/11 GI Bill and another GI Bill benefit.
The Post-9/11 Veterans Educational Assistance Improvements Act of 2010 (Public Law 111-377) changed this effective Aug. 1, 2011, adding the requirement that you would need at least two periods of qualifying active duty to be eligible for the Post-9/11 GI Bill and another GI Bill benefit.
If you first entered active duty after Aug. 1, 2011, you need at least 2 periods of qualifying active-duty service to qualify for this additional benefit.
For example:
1. You had one period of active duty from Nov. 10, 2005 - Nov. 9, 2009 and received an honorable discharge
2. You also used 36 months of Montgomery GI Bill - Active Duty (MGIB)
In this case, you would be eligible for up to an additional 12 months of the Post-9/11 GI Bill.
However, if you initially entered active duty on or after Aug. 1, 2011, you would need to complete at least 2 periods of active duty with honorable discharges to be eligible for this additional benefit.