XPS 13 Debian - mic problem

I have Debian 8 roughly working - except the mic. I upgraded the kernel to 4.0 and have tried applying the patches Barton George suggests but this is beyond my capabilities! First the patches 'couldn't find file'. Then i saw somewhere that I could just download the patch_realtek.c file. So I tried that, downloaded to /usr/src/linux-headers folder and ran the 2 patches. They seemed to run successfully but nothing's happened and mic still not working. I've now removed the patches.

Should I have rebuilt the kernel or something? Should I have done something else with the patch_realtek.c file (installed the driver? applied it as a patch?) Please help. I really need mic working and although I did manage to upgrade kernel, I am not familiar with working on this and am worried about trying more stuff in case I mess up where I've got to. I need fairly basic instructions. Thanks

I have the Developer edition.