Termination Fee

I called direct t.v bout cable about a week ago , i was told they had internet ..THEY DIDN'T... i also got the worst signal because there is two big oak trees in front of my condo an that's the only place the dish could go so i call to cancel an they tell me I have to pay $460.00 to cancel even though I've only had the service for a week. Does anyone know what I can do I am not willing to pay that amount an all they give me is the p.o box not even a number . Help please how can i resolve this issue.