How can I get data back with Straight Talk on my 3gs

I have an iPhone 3GS that I no longer use. I gave it to my daughter and set it up on Straight Talk. Everything was working perfectly except MMS until Monday afternoon ( 7 January) when 3G just disappeared. I called Straight Talk customer service, which really *****, and was told because of an update they did, my phone will no longer connect to data. Surely there is a way for me to fix this problem, short of the fact they may just be lying to me. I had previously installed unlockit and it worked flawlessly.

Can anyone out there please help me? I'm a retired high school math teacher but I still would need your advice to be step by step.

Any help would be so very appreciated.