The watch casing on my forerunner 645 Music is damaged and local support center says it's my fault.
When I checked internet I saw that there are many examples of same problem which means it is a common problem. Also there is a Garmin related to the problem.
https://support.garmin.com/en-US/?faq=fWW1dV4Y3O9RufIvQqEyG7
It says
If you notice damage to your watch near where the watch band connects to the case as shown below, the watch will need to be replaced.
You can request an exchange using the following tool: Garmin's Online Exchange for the Forerunner 645
And here is my demaged case:
The explanation above says nothing about warrant period, serial number etc., but when I called support center, they said if it is in warrany then it is OK, but if not, there will be a cost for replacement which is 118 Pound for England.