Sidi loves to criticize Victor Cheng's methods, ha! :) Srsly - I agree with what he just wrote, do not use the "business framework" as a catch all and simply call it a day: there still needs to be progression and logic, lest is just becomes a semi-random list of buckets that have no apparent link between them. Anyone can draw lines, that doesn't make us architects.
The creativity piece is harder to fix. When you build your framework at the beginning, you obviously don't know the solution yet. I often suspect interviewers complain about your "lack of creativity" as a cop-out when you didn't do well enough but they can't exactly put the finger on the problem. I recommend you focus on really addressing the issue and build a detailed framework at first, even if it will sometimes appear fairly standard and boring. An objective here is to have such a solid structure that you can then free up more of your mental bandwith to cracking the case vs. trying to remember what you are supposed to do in a case. You will be able to display your creativity within each of these buckets and in the recommendation piece.
Serdar, sorry about the rejection. I know it hurts, but I appreciate that you are already focused on getting better. I hope the above helps. Let me know if not, I'll take another crack at it.