I have recently bought a Ford KA, it must have had a bump next to the rear bumber on the driver side, and it looks like someone has attempted to fix it themselves, and made a really bad job of it. There is a crack in the body work that they have done, it looks really matt (not shiny at all) and really rubbish. I was wondering if anyone could suggest a product that I could use for this? I would really appreciate the help.
Or if anyone knows how much it would cost to have done?

Thank you in advance!!