Can you describe what you mean by getting the run around? Are they giving you feedback that they're unhappy with the result and don't want to pay you? Are they saying/implying that they don't have enough money and can't pay you? Is this your only client? How many months behind are they? Do you have other prospects so that you could walk away from this client today and be okay financially?
With all due respect to the advice posted so far, it's difficult to offer useful advice without a bit more information about your situation.
With all due respect to the advice posted so far, it's difficult to offer useful advice without a bit more information about your situation.