I'm having this problem. I have reported it 3 times and have been told by separate help-chat-people to just wait. The photo I want removed is over a year old now. I respect that you may have got yourself in a design/development pickle, but you must understand the emotional response (unwanted) photos have, and the negative effect this has on the experience of a key feature of your software.
I deleted my Facebook account a long time ago, so I can't update it there, or re-sync accounts or anything.
I'm having the same issue. I have been trying since last year sometime to have the profile picture of my ex removed but no luck. I have contact support multiple times and followed all the steps and still the same picture. I even created a new facebook account and attached it to my spotify account for over 3 months and it still won't update?? I'm really how difficult is this to fix? Or give us an option to change/update the picture.
So after a chat with 2 different persons at Spotify, I may have a solution.
It appears that you need to follow the discover weekly list in order for the profile picture to refresh, at the same time the playlist refresh each week.
If you do not want it to be your Facebook picture and only the default one, you need to stop the synchronization with your Facebook account. Once it refreshes, the picture should become the default one.
I will try that and see if it works. More news next week, ahah.
I do not think that is a great solution and clearly, they did not think this through at Spotify.