Rather than go through all the transaction info and calculations I will provide a summary of the total amounts and outcomes:

I deposited 2 MBTC for this BATMAN Promo and was advised that I won a wheel spin. 

Prior to making my depo I opted OUT of the 50% deposit bonus that is pre-selected for you in their cashier.  I said no thanks. 

But after the depo was confirmed, I then was offered spin on the wheel for this BATMAN promo.

I spun the wheel and got 10 spins yayy (the lowest amount possible on the wheel) which I was fine with. 

Okay 10 spins. And the winnings have a 40x playthrough.  Okay sure. 

But here's where it becomes strange. 

Free Spins begin, I have 10 spins total.
Fast forward to the end, I finished with winnings of 0.000302 BTC or 0.3 mbtc!

Hardly any winnings at all.  But okay. X40 playthrough gives me a wagering requirement 0.012 approx or 12.3 MBTC
These numbers are confirmed in the promo section of my account.  It shows these numbers in their respective columns.

So remember I had deposited 2 mbtc so now I have 0.002302 BTC OR 2.3 MBTC TOTAL. Wow. Not exactly what I had hoped for but that's fine.  Maybe an unlikely set of freespins.  It happens. No problem.   Moving on. 

So now I take my 2.3 MBTC and play for a while and while. 
My lowest balance was only 1.3 MBTC and to my surprise I worked my way all the way through that playthrough.

With 99% of the playthrough completed my balance was 8.7 MBTC.  A nice amount I thought. 

So at this point there is only a few spins left until I hit the 100% and finally clear that playthrough to unlock my free spins winnings which we recall from earlier was 0.000302 BTC or 0.3 mbtc. 

100% achieved.  Yayyy.  I made it right? Nice day of wagering. 8.7 MBTC nice little come up right? WRONG

I look up and suddenly my balance has changed from 8.7MBTC to 3.3MBTC. Wait whatttt? Certainly there was some error or miscalc?!? So I open live chat and explain and the agent says:

"as I can see you were using the batman promo which has a maximum of 3.3MBTC for the freespins"

"....For the freespins" were her exact words. 

I didn't see that listed anywhere prior but ya know what, I accept it as they say.  Maybe there were some fine print, not the most ethical practice but I've seen it many times Plus I only won a small amount on the freespins of 0.3mbtc so the Max of 3.3 MBTC WINNINGS on the freespins should not affect me anyways. 

So I stand my position that there is an error. 

The support agent says "no sorry thats the Max win for this promo"

At this point I see that they are fully aware of my balance details and are miscategorizing my funds as being from the freespins which had a hidden maximum winnings restriction.

This is one of the sleight of hand type of shady behavior that I wouldn't normally expect from what appears to be a reputable website.