PTCL Broadband sucks? Yeah it does. I am suffering from last two days. I cannot open a web page. Firefox just "Looks up" and Chrome tells me there is "dns resolve problem". I call them and file a complaint. After a few hours it gets restored but the next day same problem. It really sucks when you are in a mood to work and there is not internet despite of no loadshedding. So this time I changed the DNS server to Open DNS. It provides good functionality including content filtering and network stats etc. You can manage your home network very well through Open DNS. So go to Opendns.com and get their registered (its free!). Select Home for account type and then proceed with registration. Afterwards it will guide you to setup open DNS on your computer, router etc. Follow detailed step by step guide with screenshots and get rid of your ISP's crawling DNS service.
PS: If you are already a geek and know how to change DNS these are the addresses. Go to your network properties, IPv4 properties and change DNS server address to these: