Do u feel the voice is also louder than before? if yes, may be some milk accidentally get into the pump. Let's call their hotline 2332 3366 for help first.
If they can repair for u, then let's bring it to Cheung Sai Wan head office, they can repair for u immediately. Cos I went there to repair it yesterday, only 30 mins ! If u bring it to the sale shop then u need to wait for 1-2 weeks!