个人经验:
建议正式书面地说I am disputing a charge on my bill dated xx/xx/xx in amount of $xxx. I never requested this service from this contractor, and the claimed repair was never rendered.
简要叙述事情经过,以便万一管理人员不清楚前因后果,只是在例行公事。附上证据管理公司的工人没有修门,你们也没有要求他修。
保留备份留作法庭证据。