Said like this, your first paragraph, the first thing that crossed my mind was, "that looks more like an attempt of installment, not an investigation." But with your explanation on the paragraph that followed, I guess it can be argued that yes, there were very few, perhaps even none, casino that allows such leniency during investigation. Of course, assuming that this is indeed an investigation requested by your provider instead of an installment attempt.
I understand what you are saying, but the truth is that we are a small team and we are not currently able to resolve these cases as quickly as we would like to.
We have had similar problems before, because this user and many other users before this one (or multi-accounts of this user) have a similar and suspicious playing pattern (among other things), so we have suspected for a while now that there could be some exploit in our games and we are still investigating as fast as we can, but we decided to give him the option to slowly withdraw his winnings in order not to harm him that much.
We know that this is annoying and time-consuming, but we are doing it for our sake and the sake of our legitimate users. We are an honest casino, we have had these problems before and we have always managed to resolve them in the best possible way, which there is plenty of evidence of in our
main topic on this forum.
Pure curiosity, suppose OP managed to withdraw 10mBTC before you can finish your investigation and managed to learn that OP actually [let's assume for the sake of a narrative here] cheated the system, completely and entirely, through and through. You'll absorb the loss suffered from his withdrawal that he's not legally entitled to? Again, pure curiosity, I'm not scrutinizing or doubting you here.
[...] But in any case, this user should just contact the support team and wait for a response to regain access to his account.
This part I am strongly agree.
OP, throttle back a little on your ticket, if you can? And then throttle further back, and stop harrasing the representative's personal contact. You're kinda lucky that this casino seems to be a bit lenient, other casinos would kick you out just for harrasing their staffs and/or using bad language.