2010 Hyundai ix35 Premium 4WD - Road speed indication missing from ix35 Satnav - casey

After a software 'upgrade' in May 2011 I lost the road speed indication feature from the Satnav.For me the most useful feature of it, since it does not have full postal address either. It was suggested at the time that another imminent 'upgrade' might restore the feature, however after two 'upgrades' and the recent replacement of the media screen, nothing has changed.The indication has not disappeared completely, it appears intermittently, most often on motorways (just where you need it). Navteq tell me it is not a maps software issue and the indication should be there if selected. Hyundai 'technical' support have been patronising at best, and incompetent at worst, telling me that 'upgrades' sometimes remove features, and that this is perhaps the case here-in other words tough luck go away. The dealer has been very understanding, but it appears they are getting the same technical support as I have had. Before anyone suggests it, yes it has been selected in the menu! Does anyone have any ideas or advice?