Vauxhall Zafira Brake Caliper Problems

brake disc and pads replaced january, new tyres january. this week a knocking noise from the wheel, found balance weights knocking on the brake calipers, why would this happen? and why after two months of changing the brakes and tyre.

Originally my car wouldn't start when the engine was warm unless I kept my foot on the accelerator and put it into drive whilst pressing brake too. Once it was going, the idle speed fluctuated at traffic lights or in slow traffic and often ...