Bad service

I have purchased a Tom-tom Via135 navigation unit on the 5th of March 2015 by salesperson 2773 at Makro in Alberton Johannesburg who did not inform me about registering my product in the 30 day period after purchase, however, I have been using the unit until July 2015, that's when the unit stays on searching for satellites. Only then was I told about the product registration in order for the unit to start operating again in 10 days after the registration. I've followed the instruction and it now being the end of August my Tom-Tom is still not working, the tracking on tom-toms website says that my claim is invalid, I am truly dissatisfied as the unit is not even a year old and is now completely useless. I am a sales rep and rely on a navigation unit to get around.