How is it not obvious to the NF support team that it should be impossible to have 41 stacks of 99 keys?
If we can only earn one key per day, it would take over 11 years to earn that many.
I have been mostly ignoring them since they started, and I only have 4 stacks (just over a year's worth) - so this definitely sounds like some kind of glitch on their end.

The fact that they all just showed up, and keep reappearing, should be a red flag to support. Imagine if you had 50,000 Ironite mysteriously appear in your game, and no matter how much you tried to spend it down, it would keep resetting to 50,000 Ironite. They would no doubt send a full strike team into your account to delete this rogue asset in a heartbeat. So it puzzles me how they are just shrugging this off like it is no big deal.

I feel your pain, and I hope that this gets sorted out quickly...