problem with sat nav and bluetooth

Hi, just joined today so apologies if I get this wrong!!

Have Megane Coupe dci 61 plate, both sat nav and bluetooth not working. Sat nav says no maps found, bluetooth won't connect to phone book. Been told new SD card (over £100) will resolve both issues, but reading forums I am wondering if this is actually the case or am I being fed a line?!

Any advice would be great

Thanks