CONNECT and T-Mobile problem

A week ago I took delivery of a new Alfa 156 Sportwagon GTA which is
every bit as good as I hoped, it's fantastic fun to drive!

The one minor irritation is that I cannot get the CONNECT hands free GSM
phone system working with a T-Mobile pay as you go SIM card, it simply
can't find the T-Mobile network, it only seems to recognise the Cellnet
(O2) and Vodaphone networks.

The system appears to have around 200 mobile networks predefined but not
T-Mobile UK, a quick check on the internet has identified 3 network
addresses that T-Mobile use and I have tried to add these into the
system following the instructions in the manual however to no avail as
it doesn't seem to store them properly.

I have tried getting the dealer to help but the sales guy didn't even
know how to insert the SIM card correctly and simply started reading the
manual which I had already done.

If anyone has any experience of using/configuring the CONNECT system
with T-Mobile UK or successfully adding a new network I would be most
grateful for some assistance.

Glen