This is probably of no use but here is the location of the latest Navcore 11 maps on TomTom website
[Please Register or Login to download file]
where XXyXX are the map names eg Southern_Africa or Africa etc.
eg
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[Please Register or Login to download file]
Also replace 890 with 885 etc for older maps.
The .ttpgk appear to be some (compressed) archive format of sorts.