Saws-All, sledge hammer, copy of survey and copy of the returned certified mail to show the good faith attempt to allow them to resolve their error and in-case police are called, and a few friends to help lift sections of the fence. You could have it down in 2 hours. Beer and BBQ to thank friends and celebrate the re-annexation of Crimea. You can buy the saw and sledge at Harbor Freight for under $50 total probably, $50 on BBQ, and $50 on booze ~ $150.