6310i GPRS problem (Optus Australia)

I have a Nokia 6310i that will no longer connect to Optus Zoo using GPRS. (I used to be able to view emails by connecting through GPRS).

I now receive error messages such as 'File too large to be loaded' or 'Couldn't reach the indicated web server'.

I have tried Tech Support both at Optus and at Nokia. In the end Optus said the phone is just too old.

Does anybody know how to overcome this problem?

Thanks, Regards, Glen, Sydney, Australia.