Connecting PS3 to the internet using an o2 dongle

Hope I'm not asking an already overly-asked question, but I'm flipping raging about this now. I'm having a nightmare time connecting my PS3 to the internet using the dongle. I'm living in the countryside right now, so wireless broadband isn't an potion for me. Instead, I've been connecting the laptop to the console using an ethernet cable. This worked for me several times a year ago, but since then I've just been getting a "could not get IP address" message (not quote).

Recently, I've realised the dongle reset its IP address every time I've connected to the internet,so I would need to manually input the new IP address every time I connect to the PSN. Howver, i've run into a new brick wall now - I get a "DSN error" message after I successfully find my IP address, but fail to connect ot the internet.

I thought I might need to get a PPPoE username and password from o2, but when I requested it online I was just told it would't work, and that I would need to get a proper modem to connect the PS3 - which is odd, considering I distinctly remember downloading a Rock Band album using the dongle before.

I've tried using Connectify too, but I get the same error code (80701020). If anyone had ANY ideas how to get the console onto the net short of moving hous, I would appreciate it SO DARN MUCH