Astra 2017 Sat Nav Update

[snapman]

Need a wee bit of help with how I can update the Sat Nav on an Astra 2017 plate, registered on the 01/03/2017. I've looked online, and paying through the nose from Vauxhall is not an option, or online buying sites. I'd rather come to DW where the info will be trusted.

Thanks in advance,

snap