Amundsen sd card missing

Hi all ive recently purchased a 2012 skoda fabia monte carlo ..the system is a. Amundsen satnav unit but there is no sd card in the unit ..can someone point me in the right direction to either buy a second had card for this unit or is there an alternative way to load updated maps 

Ie: buy an sd card and load maps from portal ..if i can buy an sd card which 1 is best to buy and what size gb do i buy 

THI 

Mike