When you say update the Sat-nav, I presume you mean update the mapping rather that the system? If so, that's not something dealers do as it takes too long (can be 3-4 hours as it makes a full backup first and the mapping server is a bit slow); at least I've never heard of a dealer who will do it. It's an owner operation, done using the Mazda Toolbox software that needs to be installed on your computer. The only updating that a dealer would do is to the infotainment system, which is done with a direct connection to the car, not via the SD card.
Haven't heard of the other problem before, though. I think you need to go back and have a word...