How do I improve my English language?

My grade for English language was an C. Despite the fact my literature grade was an A, my history an A* and RS an A*. This obviously shows that I'm able to communicate well using English. Honestly I don't know were I went wrong. If it's possible I will retake, but I don't know how to improve my grade because I have no feedback whatsoever. I don't know my coursework grade (I think it's a B) and I was not shown any marks (neither raw nor ums marks) so I don't know how well I did. I have no feedback on what went wrong at all. I'm not rich, and I really wouldn't like to ask my mum to pay to see scripts and all. I already feel guilty to ask for a remark.

I always thought English was a tricky subject to improve on, with maths and science there is pretty much a wrong and right answer which helps. How do they expect me to improve with no sense of direction or feedback? I'm completely lost as how to improve, I was quite confident this earlier this year with me getting A* but now all confidence I had has diminished. I feel like I am illiterate.

What can I do? Just passed papers, unfortunately I'm doing a new kind of CIE paper which the last question has slightly changed so I'm also confused but that part.

Sorry this is so long.