Just stop seeing that ML and try another ML. If majority of the MLs in one shop does the same thing then you're better off going somewhere else.
I had visited a shop when they first opened few years back. During that time most of the girls were very dodgy - asking for $100 tip instead of $50. I stopped seeing each and every one that asked for more than $50 tip, and that teaches them a lesson as they get less popular and soon stopped working there. Only girls that remained were those who stick to the $50 tip and doesn't offer more than part 2. They know better that by restricting to strictly part 2 (no part 2.5, 3, 4 and so on) that they'll get inundated with more customers wanting to experience quality massage.