Sorry, i'm way too lazy to read through this entire thread. But, i had the same problem and it was definitely ISP related. Sadly, at the time, all i had was my mweb account but thankfully, someone uploaded the update file that i needed to rapidshare and, after downloading it, i simply used a proxy to get it onto the ps3.
Have you tried a different isp? If you don't have another isp account, why not just go onto axxess's website and get one of those free 3gb trials. You get the login details instantly.
PS i'm not advertising axxess at all! Im on openweb now but i've tried the axxess trial and it literally took 2 minutes to get an account. Maybe its the same with other isps too...