"I want wal-mart to honor it's "WRITTEN" public return policy, not some crap that the CSM decides to make up because they are too lazy to do the return."

Unwarranted accusation. It may be easier to do the return rather than debate the customer over the return. Therefore, laziness probably has nothing to do with it.

It is more likely that the return policy changed without notice or the employee was not clear on the return policy.

In addition, did the OP speak to a manager? The second paragraph states it was a CSR, but the fourth paragraph uses CSM terminology. Which was it? I would have tried someone higher up if it was the
former.

The return probably should have been accepted. I would rewrite the letter leaving out the accusations of fraud, laziness and threats to get an attorney.