Dont know about Tavion Navigator but you could try the teleatlas or navteq maps in the igo section, they have the .fbl extension. Remember to backup first
I think maybe you mean Tevion Navigator--a 3.5" unit sold through Aldi (and perhaps others) a few years ago? Does it look like this? [Please Register or Login to download file]
In any case, the brand of the unit is not as important as the software running on it--is it iGO or something similar? If so, you need to determine the version and then find appropriate maps.
As near as I can determine, I think that unit is running a rebranded version of My-Guide 2006--which was made by Nav-N-Go as a rebranded custom version of iGo MyWay 2006. If you could find any maps for iGo MyWay 2006, they might work. But it is unlikely that any maps you find will be newer than what you may already have, as the software has basically been abandoned.