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. It could take up to 10 days to be returned from the banks. 

It says the routing (ABA) number is incorrect, but it is the correct one on my check book.

If it is a wire, sometimes bank have a different routing number (ABA) to the one on your check book (ACH routing number). Please chack you are using the correct one for a Wire versus an ACH. you can call your bank or search using google for routing numbers for your bank. 

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 delete the bank details. and re-add being careful to check for any errors.