[Baron Munchausen]

Cute, but not effective. Since the formula is effectively illegible (no ordinary clerk will be able to figure it out) they can claim you are refusing payment. A more effective older trick was to mess with the billing system by finding technical grounds for claiming small refunds (on the order of a few cents at a time) and then not cashing the checks. This forces the phone company to keep every increasing mountains of records. Of course, that was in the 1960s when "records" actually meant paper. Today I suppose it wouldn't do much damage to make them keep a few more entries in their computerized accounting records.