Why are BT call centres so terrible?

I have been wanting to ring up and make a enquiry about BT line rental for days now. I have been in a que 5 times now!, each lasting 30 minutes each before giving up,all at different times of the day! Why on earth are BT so terrible with actually answering calls, i mean by the sound of things they must have like 1 person running the whole call cente. I really need to talk to them but these bloody ques annoy me. Anyone else have the same problem.