What can i try next.

I may be confusing you let me start again. The first i new of this problem was i would drive down the road all ok put the wheels on full lock i would get a grinding noise and my warning allarms would come up and my brakes would seem like i didnt have any. Then it would clear and all be ok. So i was informed on hear it was prob my bearing so i had it changed. Since i had it changed my warning lights come on as soon as i pull away but my brakes are all fine.So people on hear sugested i need to adjust the sensor but every time we adjust the sensor and the lights go out when you brake there feels like there are no brakes again. So it seams like the sensor is working in reverse. Can any one tell me what i need to do or is anyone local who can have a look. I need to sort this as my MOT is due very soon.