What level of service is your cousin paying for? Around here you can purchase DSL service at speeds ranging from 750 Kbps to 6 or even 10 Mbps depending on location and how much you are willing to pay. There are lots of variables besides those already mentioned including the possibility, if the connections are wireless, neighbors camping on the signal and using up the bandwidth.
The place I would start is finding out what level of service is being paid for and then use a reliable speed test such as
WhatIsMyIP to see how much of that your cousin is actually getting. Do not expect to get 100%, that will seldom happen, 80 to 90% is not untypical.
