A lot of finance companies have rejected me for placements for low A level grades despite high firsts in all my CS modules, solid extra curricular's etc...
Hence companies relying on A-Level scores and university reputation when filtering.
What ECs do you have ? - that's probably your best bet of getting visibility. Assuming you're a second year student you might want to apply for a GSoC on a low-level project.
All I can say is keep at it but remember, especially for grads, they get a million CVs.