A council meeting is a meeting of councillors, and members of the public (although entitled to attend) have no right to speak except to the extent specified in the standing orders. Larger councils generally restrict this to a defined period and place time limits. Some smaller councils have adopted a more relaxed approach and permit members of the public to make comments during agenda items. However, the chairman must always maintain control of the meeting. There are no specific statutory rules on the powers of the chairman, but they are more or less absolute. The powers of the chairman derive from common law and the standing orders. Thus, I'm afraid the chair is within their rights to rule that spoken prompts are not allowed. However, I'm sure you should persevere in putting right incorrect claims, by whatever means you can!