Try re-spraying the cap its cheaper.
The mirror will take a hit and you can reposition it, although it makes nasty click when you do.
I'm less impressed however that any housing damage results in a new mirror, when the wife forgot to fold the mirrors reversing out of our garage it flicked the cover off with practically no damage, but destroyed the housing.
Because the cover could be reused I paid around £200 for a new one, the car was only a few weeks old!
To be fair to the wife she has never had a accident, other than that, in forty years, I hope I don't regret posting that, while I must have had around six, luckily though none since 2004.
I now have a front and rear dash cam, both bought for under £60. But they won't pick up a side impact.