Sat Nav issues

I bought a 4.3" iGo  sat nav by MKelectronics at the Glasgow Caravan Show in February. The unit has allowance for towing caravans, ie you input dimensions and routes are selected to suit. It seems to work well enough but there was little documentation and maps are out of date. I have tried to communicate with the supplier but they do not respond to emails and do not call back on their phone lines. Has anyone had a similar experience and did they manage to overcome their problems?