occasionally (1 every 10 times) the passenger mirror doesn't unfold. I have to close the driver mirror and then reopen  again which then opens both of them. How long would you put up with this before getting it fixed? I'm thinking it could be expensive to find an intetrmittant fault like this. thanks

I have mine set to fold/unfold when the car is locked/unlocked with the key fob. On about two/three occasions in three years, they have not unfolded when unlocking, so have had to do it with the mirror button on front door. Always both, not one like yours!