GPS problem - persistently trying to make me drive on cycle paths

I had a similar issue in Strasbourg where the sat nag constantly tried to re-route me through a road that was closed (with a barrier) at key times of day. We arrived whilst the barrier was closed and couldn't get to our hotel (although we didn't know this as the time), but there was an alternative route but the sat nav just wouldn't re-route to it. In the end it was so busy trying to re-route itself back onto the barrier road it blue screened and then put up a message telling us to go straight to Audi service! Thankfully after 5 minutes being turned off it sorted itself out, and we were able to get directions from local shop, but there are obviously odd occasions where it will have a mind of it's own and will under no circumstance offer an alternative. Probably more down to the mapping company than the nag as it's only following the rules as set out by them. May be worth mentioning this to Audi though as unlike my issue, driving up a cycle path is more serious!