I am not a lawyer. I think a mistake many people make in ongoing situations like these is contacting (and thereby deferring to) a companies 'support' channel. By asking them to reconsider, you almost subject yourself to their authority. If you believe you have a legal dispute, you should write to them officially, cc your legal advisor if you have one. Given the sums involved I would personally take professional legal…
[1] http://www.businessinsider.com/google-search-ad-policies-cos...