iPhone 5 not connecting email to straight talk

I bought a verizon iphone 5 from Amazon. I used it on Straight Talk and it worked fine. My phone number also used to be Verizon. Then my Sim card was not getting everywhere so they sent me a new one. Now I don't get email or internet unless I'm under wifi. I want my phone to work like it did! I've been on the phone with Straight Talk for two weeks now and they are not able to solve my issue and I'm not able to use my old SIM card that actually worked anymore. My phone's APN settings says Straight Talk is not verified and it says tfdata for the APN name. It should read VZWINTERNET. Can Apple help me with this issue or maybe Verizon? I can use phone and text but do not have email and Internet access. Says it could not activate cellular data network.