I agree with Hamid. The person disappeared after making the post. Said he would make some complaints with NFA and such. Hes full of non-sense and people are way to quick to jump on the "scam" bandwagon.
Notice how the person claiming they are a scam is the same person who acknowledges they are bounching ACH deposits. This incurs a fee anywhere. His mess started when he did not have the funds in his account to deposit. He trades with these funds that where not his. No doubt he most likely had losses as well (of funds that where not his). He needs to deposit enough to pay for all fees and lost funds. He did not come back and report anything. Nadex takes all inquiries seriously.
I personally have traded Nadex for years and have no issues with money being deposited or withdrawn and don't know a single person who does and i know 1,000's of nadex traders. Though I rarely do deposits as the goal is to take it out not put it in. Here is a sections showing many recent withdrawals from Nadex with zero delay. forum.apexinvesting.com/t/the-goal-of-trading-for-any-trader-is/4425/2
There is no scam here just someone who can not manage their own funds to not place a deposit for money of which they don't have to deposit and causing themselves an accounting nightmare and wondering why someone does not give them free money.
Nadex is not a broker it is an exchange. it does not trade against you and its funds are held in segregated accounts. They are regulated by the CFTC that is higher than the NFA as they are an exchange.
In addition, they are an exchange not some pee on cyprus broker they are not going to publicly reply about someone's private account.