When you are paying for a meeting it must have an agenda
There seems to be a tendency on the part of some vendors/partners to skip producing an agenda for a meeting that clients are paying for. This is not acceptable. No paid for sessions should be done 'on the hoof'.
A meeting agenda should be clear about:
who owns or is leading the meeting
what pre-requisite preparation is required from attendees
who is expected to attend
what will be done during the meeting
what is the intended outcome of the meeting
what will be the output from the meeting
This may seem like a lot but it should only take a few mintes to prepare and send out.
Now everyone's expectations are in-sync and the PM can hold the vendor accountable for the successful delivery of the meeting, when it comes to paying the bill.