My Model 3 has mysteriously lost 15 miles of range.... My range was 315 miles for 9 months and after charging on April 22 my range dropped to 300 miles I have contacted Tesla and I am getting several explanations but none really make sense. Thoughts?

My Model 3 has mysteriously lost 15 miles of range....

(I thought I was getting 10 additional miles of range with the new update)

My Model 3  has always had 315-320 miles for 9 months and after charging on April 22 my range dropped to 300 miles.

I contacted my local Tesla Service and I was given several excuses but no true explanation.  I did receive a text  that did acknowledge my loss of range as a known problem  and Tesla is aware of this "glitch".... Tesla said a firmware update will fix it, but Tesla can not tell me when this firmware update "fix" will be available.

 Has anyone else had this problem? 

Thank you Thoughts?