Ubuntu image for Inspiron 15R 5520

Hi,

I have bought Dell Inspiron 15R 5520 notebook, with pre-installed Ubuntu 12.04 LTS image. I formatted the recovery partition to try Windows. Now, as it turns out, I can't use any Linux distro, without Dell's special drivers. Canonical says this machine is certified for  Ubuntu, however, the image available for download, is lacking some of the drivers (AMD Radeon 7670M graphics), or they don't work well. Particularly I'm having problem with the USB 3.0 ports, when using peripheral devices. Whenever I dismount the external HDD, it automatically re-mounts in a fraction of a second, and it seems no command can power it down.

I cannot use Dell Downloads for preinstalled software because my service tag isn't supported. Is there any way, to obtain the OEM Ubuntu 12.04 LTS image, or at least the required drivers?

Thanks.