Knocking as I slowly brake and ABS lights on

Hi, I recently had all new brakes done, The man who done it then said I needed ne spring arm and wheel bearings,which he done. Since then There is a knocking when I brake slowly and the ABS lights are on constant. I took it to a garage and they said the bearings could be te wrong way around or it could be the sensors?? Any  help or advice would be great Thankyou. :)