Behold and T-Mobile Data Plan Help

I had a Samsung Gravity T go bad and I had to dig out an old Samsung Behold (1) to replace it.

When I originally used the Behold, it had been on a T-Zones data plan and I probably had hacked the data settings to get it to work.

Currently, that line of service is on a phone first loyalty data plan. Not sure exact name of it, but I'm paying $5/mo for it and it worked with the Gravity T. The T-Mobile website did automatically pick up that I'm using a Behold now.

With the Behold, if I try to go to the internet, I get an error saying subscription upgrade required. I called T-Mobile and they said that the Behold isn't compatible with this data plan and that I need to upgrade to a full data plan, which there's no way I'm paying for on this phone.

Is there any way to get data to work on either this plan or some other plan (like could I get T-Zones back?) that I could talk loyalty into giving me? Any settings that I could hack again to get data working?