Well, there is some truth to the length of a phone line thing. It IS a critical part of your connection and the longer it is the more likely it is to have some sort of flaw in it or be affected by outside interference which can greatly affect the speed and reliability of your connection. Is it the likeliest source of problems? Well no but it's easier, faster and cheaper to test than to send a tech guy to your local -whatever it's called, phone hub station thingamabob- or to your home.
Glad things worked out for you though!