Has anyone else had this? We have only been using the parent handset part for a couple of weeks since moving our son into his own room. Last night, despite the handset being on charge all day, it started beeping low battery within two hours and tonight, as soon as our son makes a noise or movement instead of hearing him its making a horrendous loud noise, I cant even explain what its like! Its not a static or mobile interference noise. I have had to switch it off completely as its so loud its been waking him down the hall. Just wondered if this is common before I trek to mothercare to return it x