Here's a tip: Use a site like localbitcoins.com to sell your bitcoin and you should never have a problem like this, plus it will be all done within an hour usually. Looks like coinbase have a poor setup for exchanging into USD, but not necessarily fraudulent. It does suck to lose a 3rd of the value, just use it as a learning experience. The trouble with sites like coinbase is once they achieve such a large scale, they will become targets for government monitoring and are required to log more.
They are somewhat improving it, especially with their new feature where you transfer US dollars to them and can buy bitcoin at a later point in time. More like an exchange
I do agree that LBC will probably be better for a lot of people wanting to do cash trades (although you would not be able to trade from the comfort of your home as you could with coinbase and LBC generally will make you pay a larger spread)