uFone GPRS issue

i have a ufone sim, but i have never been able to use gprs on that sim, changed and tried many phones no luck. i've called the customer service many times, i have the required settings installed, the ufone customer service rep says the gprs is activated but NO LUCK yet. another one i called told me it will work within one day (by 11pm today i suppose).

what could be the problem waise?