Help with downloading maps for the standard Amundsen Stereo

Hi, I have an Octavia 2010 1.6 tdi which i purchased a few months ago. It was fitted with the Bolero stereo but I soon purchased a second hand standard Amundsen stereo (RNS310) and installed it along with the gps antenna. Unfortunately it did not come with the navigation disc or sd card and was wondering if someone could give me some advise about downloading the appropriate maps in order for the sat nav to work. I have tried a couple of torrent downloads which i burnt onto cd and sd card but none of them worked. I inserted the cd and it would read it for a couple of minutes, spit it out, suck it back in again, read it again and so on until it would come up with an error message.   I have attached a photo of the stereo I am talking about incase of any confusion.

Any help on this situation would be most appreciated as searching through forums is driving me mad with confusion. Thanks Sam