singular knock noise when braking and then when pulling away atto 3

has anyone experienced a single knock noise when braking then when pulling away again . atto 3 16k miles ive had the car from new and its been an ongoing issue that i feel the garage are just throwing parts at but dont seem to know what the cause is , over the last 8 months they have fitted 3 drive shafts , a steering Colum , front wheel bearings ( was confused by this as noise isnt constant or a rumble } , the issue still isnt resolved and they are now trying to fob off with some nonsense of a floating caliper than all models make this noise some just louder than other which im not accepting as a reasonable explanation or outcome