It sounds like you're bad at sophisticated writing. This can be fixed by doing the following:
- Read a lot of high-quality critical writing (literary theory is great for this but often boring. Maybe start with Roger Ebert's film reviews?)
- Read past student essays
- Try to emulate these styles in your own writing
^agreed except for the first reason.
Anyway, don't move down to standard you'll get screwed over by the scaling. How bad are you doing exactly?
English is a subject based on understanding over memorising, (of course techniques and how they're used for an author to effectively convey his/her message often has to be memorised, you still have to understand how they're used in their respective texts and contexts) So it isn't just simply input formula or regurgitate information mate.
Pretty much if you can grasp the concepts, and convey them effectively to the reader, through use of appropriate words and structure you'll be able to do fine in english.
But yeah, don't drop down to standard, or Board of Studies will nerf down your atar marks like there's no tomorrow, especially if you go to a low ranking school. Might be even a better idea for the folks at your school to carry you.