Your situation is very frustrating! Though rare, it is possible to develop Botox antibodies over time which would decrease the product's effectiveness. Xeomin and Dysport are alternatives. The other possibility is that your Botox is being watered down which is a common practice depending on...
The price of Botox operation depends on several factors such as the difficulty of your case and your request for your operation area.
In my practice, prices for Botox operation reaches from 325 Euro up to 350 Euro range. If you want to learn more you can visit my profile.
I don't think anything is "happening to your" besides stimulating the facial nerve that moves the forehead muscles. The good news is that if you don't like it in 3 months it should be totally gone. I would recommend that you relax and don't panic, follow up with a doctor and just...