You are never guaranteed a blue response.
If you are not receiving the Bananas pet, you need to file a bug report in-game or add your voice to the thread in the Bug Report forum. QA and the Devs don’t take feedback and bug reports from the Customer Support forum and the SFAs here are not liaisons with them.
Here is the tread from the Bug Report forum. If you post there, include the additional information you have about your pre-exisiting Bananas pet possibly blocking your receiving of the Charity one.