DDJ SX starts playing track just by touch frame or Bang on table top...

I got my Pioneer DDJ SX Controller 1st December 2012, but just two weeks into trying it out, i noticed it would start playing a cued track on the left side (Channel 1 & 3) without a touch of a button and at certain times i just had to load a track and bang my table top an the track automatically start playing then after a few hours just touch of the metal surface of the unit, the same behaviour would be observed. I've been in touch with the retailer DJSTOP Lower Addiscombe Road 

Croydon who claimed to be the best pioneer dealer in the trade only to receive a response aimed at dodging my refund request. I've noticed few other DJ's in the USA with similar fault, but what i would like to know is the cause for a unit only two weeks old to behave like this. 

Very disappointed with unit and supplier