NVA-SD8110EU - maps removed to update but lost them accidentally!

I've been a bit of a silly girl. My in-built sat nav started going a bit bonkers, telling me I was in places I wasn't. So after Googling the problem I decided to update the SD card. However, there wasn't enough room, so I figured removing the maps to make room for updated ones would help. Except instead of making a copy to my PC, I removed them completely (doh!) and now can't get them back. Plus the message I get when I try to install updates tells me there isn't enough room on the card now! I know there have been major issues with this and I've searched online to find out how to re-download the maps and stick the thing back to factory settings, but to no avail.
Please, can anyone help?
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Superusers
Any ideas?? I have uninstalled TTHome and reinstalled and I get this message every time :-(
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