Welcome to Justanswer.com, my name is Dustin.I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.
You could purchase a full map on a SD card, but that would only let you update the map one time. And it wo uldnt let you update the device itself, or the software.
For that reason, your best bet is going to be to order a replacement cord so that you can connect the Magellan to your computer, and update the software as well as the maps via the usb cable. You can get a replacement here for under 5$ http://amzn.to/2cOV5T2
If you have any further questions, let me know.
I strive to provide great service, and greatly appreciate a 5 star rating clicked and submitted when you are satisfied.. I always answer follow up questions.Dustin S.Senior Technician and Network Switching Systems Operator / Maintainer.