I transferred my funds using ACH or Wire but they have been returned. Why is that?

The most common reason is you incorrectly entered your bank details. Please login to your account and check they are correct. A single typo in the account number or routing code will mean the transfer will fail and be returned. 

Why did it take so long to be returned?

ACH and wire transfers are handled by banks through a clearing system. The transfer still takes place if you incorrectly entered some information but is only rejected by the receiving bank one it arrives there after 1/3 business days. Then it takes the banks another 1/3 business days to return it (unfortunately this is not in our control).

How do I correct my bank details? 

It is important to check and correct your bank details before re transferring. Login and goto 'settings' then 'bank accounts', then edit the bank details. After you have checked and corrected your bank details, you can transfer again.