Mick

Parliament has no authority, to tell May to extend A50, no matter how many times it holds a vote.

The Government of the day is the Executive and only it can revoke A50, it cannot be dictated to, to do anything. Motions and Amendments are not legally binding, the government can ignore them.

As for Bill's - Queen's consent would be required on a Bill that interferes with Royal Prerogative powers, because Parliament is trying to set a precedent by trying to steal executive powers it does not have and without her majesty's consent, can stop dead any Bill and debate put forward, it's existence provides the monarch and her government with a tool for blocking debate on certain subjects if bills are tabled by backbench rebels or the opposition.