Usually, if you buy a (new) TomTom with a "free" lifetime maps, it is only for the (one) existing/current map(s) installed on the device. So, if that applies to your TomTom, you'd be able to get maps for South Africa (for life). To get a TomTom map for Australia, just go to the tomtom website, (www.tomtom.com) and click on "Maps & Services" ... and you'll be able to select and buy/subscribe to the map(s) you want.
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Usually, if you buy a (new) TomTom with a "free" lifetime maps, it is only for the (one) existing/current map(s) installed on the device. So, if that applies to your TomTom, you'd be able to get maps for South Africa (for life).
To get a TomTom map for Australia, just go to the tomtom website, (www.tomtom.com) and click on "Maps & Services" ... and you'll be able to select and buy/subscribe to the map(s) you want.