3G data does not work on my contract

For the past year or so, I find that when using my 3G data on my contract/sim, it does not send pictures or files or whatsapp, neither can I download pictures or files from whatsapp. When i try browse the internet, it just does not browse. Please don't say it is my settings on my phone, as I have checked the settings, and I have tried 3 different phones over the last yer, always thinking the phone was the problem. Please recitify this ASAP as it is impossible to work properly on my celphone.