I have Tiscali 2mb service and these are the results achieved at ADSL Guide
Downstream 1884 Kbps (235.5 KB/sec) 2034 Kbps (inc. overheads)
Upstream 243 Kbps (30.4 KB/sec) 262 Kbps (inc. overheads
If you are not getting these then I think you could have problem, it maybe a filter problem, or maybe a contention problem. Have you thought about re-installing the software for the modem, as it may need different drivers for the 2mb service.