I got my MAC code from Tiscali by speaking to its Careline Department on 0845 077 4488.
The e-mail with the MAC code arrived very soon afterwards (in fact it was sent three times in alll).
I haven't switched yet as I'm still awaiting Tiscali's assurance that it has accepted the curtailing of my contract because of its own inefficiency.
In the meantime, however, although I had to drop from 2MB capped at 2GB to 1MB unlimited, I've managed to up the speed to one-and-a-quarter MB using DrTCP...:-)
Meantime I'm having problems logging on to collect e-mails at present as my username and password are suddenly not being recognised.
That's not the first time, nor the first time my mailbox has been full although it is emptied regularly.
Even empty, it displays 26 per cent of storage capacity being in use...:-(