Had exactly the same issue (resolved temporarily after vigorous shaking - it's a known issue and quite common) last year with my OnePlus 3. TL;DR:
Definitely contact OnePlus and they'll replace the camera module for free assuming no other physical or water damage. I have in the past had mediocre experiences with OnePlus support, so was frankly astonished at the way and speed in which they handled this. Should have a year or two of life left in the phone now and certainly a new sense of brand loyalty for future purchases.
As for my experience:
- Problems started in around February.
contacted OnePlus support via official chat in late November, was asked to factory reset to see if that helped. Didn't help.
- (25/11) They fast tracked my RMA request, even though out of warranty.
- (27/11) Phone sent by courier from UK to Poland for repair (as with you, no service centres here)
- (28/11) Device repaired
- (29/11) Phone sent back to me
- (02/12) Phone received a week after being sent and camera working perfectly. Total cost to me £0.
Side note: Definitely
get a Google Camera mod once your phone is fixed if you don't already have one. Breathes a new lease of life into the camera with some software smarts. I use this one: https://www.celsoazevedo.com/files/a.../changelog849/
as recommended by the XDA Google Camera Port Hub