Hi
I had the same issue. Mine was around the grill area and quite bad!!!
anyways long story short I went to the store and they basically said its cosmetic and not covered under warranty. the brent cross store in London - manager was very rude indeed. Another manager later called me (after I complained to their customer service) and he was very nice on the phone about the issue and invited me back the store to see for himself. I went back but he wasn't there and again another manager said no way would they replace. its cosmetic issue - but nicer about it this time. I complained again as it wasn't my fault etc. I looked after the phone, no damage at all just shoddy paint job! I was advised by customer service to try another store - this time regent street in London. The were nice but again manager said nope :O( "its cosmetic and not covered under apple warranty". He confirmed he had discretion to replace the phone but unfortunately for me didn't feel it would be right to do so!
I had private insurance on the phone so decided to make a claim via them. they authorised the claim and offered to reimburse me any costs I incurred from apple for fixing the phone. I booked an appointment with apple store this time in Covent garden London. When the genie guy came over I asked how much to fix this. he looked at it and said wow that needs to be replaced. its an obvious defect!!! I could have fainted :O) he then proceeded to get me a replacement , did the paperwork and that was that. I didn't pay a penny. the replacement was made under warranty. didn't even have to make a claim with my insurer.
happy days.
so my advice is keep trying. speak and write to customer service. give them feedback and try different stores. in the first stores I tried and went on the defensive and started stating I did nothing wrong etc. at the last store I just immediately said how much to fix this? maybe its reverse psychology! lol you say left they say right, you say right they have to say left.
in some of the stores the staff can act like little hitlers - its true. but boy when you meet someone nice and kind from the stores it really helps you keep the faith in Apple. and at the end of the day that's one of the big reasons I buy Apple ... or that's one of the reasons I did!
anyways good luck!