I have been having the same problem. Original pads that came with the car were Ferodo. Installed Bendix CT on the front and got squeeling, then took the car to a mechanic who reinstalled and grinded rotors. Noise went for a week then returned. Took the car back, mechanic put a new set of CT's on and within 2 days sound was back again.
Spoke to a brake workshop who tells me this is being caused by brake dust and I should try spraying it out at the car wash. I do this once a week and it seems to get rid of it for about an hour maximum.
Have now switched back to Ferodo which are a little better but still experiencing the loudest squeeking your ears have ever heard.