Yes, they are right, but I only paid my winnings, and what was double credited left on account, so I do not understand why I am ignored.
It doesn't matter - you had the opportunity to play with 300$ instead of 150$ hence your risk to lose the whole balance was way smaller than before.
In example: You get a long losing streak so your balance crushes down from 300$ to 100$, but you manage to recover the losses all the way back beyond 300$.
Without this (let's call it) "double-spend mistake", you wouldn't have been able to do so.
For future: If you get credited more funds than you actually sent, don't even start to use this money. Always reach out to the customer support immediately before doing anything else.