Advice is usually worth what you pay for it, which is little or nothing, but since you asked, here goes.
1000 pesos X 10 sessions = 10,000 pesos. Where I come from that's not a bad piece of pocket change for a month. And assuming all other things being equal, I would guess there are a lot of pretty hot chicas who'd love to have a piece of that action. If it were me, and I was prepared to drop 10,000 pesos into a chica's purse this month, I'd be seriously looking for a discount! Or some kind of major fringe benefit.
If she then jacked the price of her services up by 50%, I'd have to start asking myself some hard questions, i.e.
1. Can I live without her?
2. Can I get equal or better service elsewhere?
3. What's next? Will it be 2000 pesos next month, and 2500 the next, and so on? If not, why not ... what will have changed?
At any rate, I wish you luck with your problem. I've been there myself a time or two