You could always try getting a tutor for maths, although I don't know how much time left you have before your exams and whether that would be a viable option.
Also, I'm not sure if you actually need maths to study computer science at university? A few friends at my uni doing computer science didn't do maths, but you probably know more about that than me. If the worst comes to the worst, you could always take a foundation year too, which is a very popular option and pretty much guarantees you doing a degree in your chosen subject.