Android phones, apps and tablets

My housemates Desire HD has really shitty signal and sometimes just stops receiving calls for a while. He called customer support and they changed his connection frequency or something and it got a bit better but is still shit. Is this a common problem or a faulty unit?

I've not noticed problems with mine. No signal on the Tube or under my building though.. refund?

Our office has shit reception, iphone 4 gets no bars, my DHD gets 1 or 2. Switching from 3g to 2g helps the iphone but I've not bothered trying on mine - the calls work.