As a parent it is a fine line - you can quite reasonably play this game without spending money and (other than this one season) it resets every twelve months and all progress is lost anyway - so I simply didn’t let mine spend anything on it.
i think the issue you face with customer service is that they deal with a lot of different games, most of which don’t face similar issues because they either don’t have an in-game chat option or are on much more stable pc or console platforms … so they don’t quite understand the vagaries of FC mobile.
i can’t offer any solution - but I have empathy for what would be particularly frustrating situation