and how expensive replacement would be? Btw my English is bad.
Break a button, speaker, mic something.
Pay visit to apple store
No way that a bumper would cause that damage.
Yes, some bumpers can cause damage like that. Fine particles of grit can find their way under the bumper between it and the phone, resulting in minute scratches.
That's damage caused by the dirt particles, not bumper alone. Unless the OP went to the beach and got sand all over the place, it looks like the culprit is defective anodized coating considering the OP is "very careful with (his) iPhone." There's no way any bumper by itself on the market would cause that damage to properly applied anodized coating.
Please read my post! I said "Fine particles of grit can find their way under the bumper between it and the phone, resulting in minute scratches."
One doesn't have to go to the beach to pick up grit! Fine particles are everywhere - in one's pockets etc.
Yes, some bumpers can cause damage like that. Fine particles of grit can find their way under the bumper between it and the phone, resulting in minute scratches.