A better ISP is definitely in order. I had this problem with a few ISPs. Ive had 2 ISPs in the last 3 years that were truly reliable. Its frustrating when they make you sign a year long contract then provide a crappy service. Make em take you to court and sue you for the money.
In the meantime, get cable DSL or ADSL depending on what country youre in.
I just got cable here in Australia and now I download at 1.5 meg per second and I never have to worry about getting disconnected, or even dialing up for that matter. Screw 5.5kps. 1.5Mbps is much more to my liking.
I downloaded 4.5 GIGs in 5 days. Try that on dial up