If you have been trying your hardest, and you believe you simply cannot grasp the concepts no matter how much sweat and blood you put into it (lets face it Extension Maths this is often the case)...then the course is simply not for you.
However if you want to do anything to do with Computer Science or Software Engineering, think again, because this is only the start of what you are expected to know at University. They expect much much more and they expect you to know everything about a area of maths in less than a week.
Scary stuff, but its reality!