Lesther case worn out
My red apple leather case is around 4/5 weeks old (same age as my phone) and the bottom part is already realy worn out (black marks)
Why or how can this happen on a 50€ case from leather? Here pictures
This is the official Apple word on cleaning, click on iPhone cases: Cleaning your Apple products - Apple Support
Since you've already changed the color you may find there suggestions to do not work and you may want to try some saddle soap or similar product ONLY ON THE STAINED AREAS. Or if you have a shoe/leather goods repair store in your area consult with them.