Latest strategy for PT job

Okay all, as some of you know from a previous thread I have a part-time job with a tea company.

Here's the latest: they are still driving me nuts because they waste a lot of my time with scheduling meetings(which they cancel cause they can't organize their time), too much emailing, etc.

Now they are saying to keep my time worked to a certain amount of hours. This is a sales/food service job and I usally work more time than I charge them for, etc.

So here's my latest plan, of which I am hoping to get your support, as I am feeling kind of good about it:

They are going to get from me the Exact amount of hours requested. When they see sales drop, I'll just let them know they're getting what they pay for.