(edit for clarity: I did receive the first deposit bonus, no issues there. However, there is no indication that this stops. The bonus message ('Get extra 100% bonus on minimum of 0.459 LTC deposit') is present to this second. This is a lock, no wiggle room).
Reading through your post and see this makes me think you have a point that their bonus notification is really confusing because it doesn’t indicate quantity it can be claimed.
I’m not sure either why the support doesn’t acknowledge your report while it’s valid concern. There’s no warning that it can be claimed once or they should just remove that note once already claimed. But since the casino has the right to remove bonuses, I think the support reply will govern. I just hope that their devs will remove that sticky bonus note because it’s really confusing to those bonus hunter that typically hunt for bonuses.