C3 binding brakes

[Ringmaster]

Hello folks,

Was happily tootling along in my C3 yesterday. Braked at T junction and heard a loud click come from the area behind the instrument cluster. Afterwards the car seemed to be sluggish. Speed didn't relate to engine revs. The brake pedal felt very firm at times. Carried on home and heard another click. Car surged forward as though liberated from some invisible force. Braked again and the car became sluggish. Splashed some water over all 4 wheels and they were steaming hot.

Me thinks I have a faulty brake booster rather than a faulty master cylinder.

Opinions, please....