I do economics (a level) which is the most similar subject to business so hopefully this will help.
1. Do you have detailed notes on all the topics that are on the advance information? if not then start there, you need to actually know the content before writing questions. Also, don't just copy from a book when you are making notes - it needs to be active so you can actually learn something e.g. read a page then write down what you remember. (google: Cornell note taking method)
2. Once you have this - make flashcards so you actively remember what you've done. You don't have enough time to handwrite these at this stage of the year as its too close to exams so just do it online, go to a library and make them/or if you have a device on 'quizlet.com'
3. Real world application. For economics if you don't have this, evidence from the case study is not enough so immerse yourself in real world examples. For example, you could look at how Ryanair use price leadership when looking at the Porter's Five Forces Model.
4. Go through your mark scheme properly and understand what every word means. Words like "analyse" and what it actually means to evaluate when misunderstood can pretty much ruin your essays so that combined with including real-world examples should boost your essays.
5. Practice makes perfect. Your teachers are your best resource, they aren't just given the title 'lecturers' like they are in uni. They are teachers because their role expands beyond that. Ask your teachers specifically what is going wrong with your essays, ask them to sit down will you and literally spell it out - take note of it and use the advice to improve. Also, you can redo essays with this new feedback and see the difference when your teacher marks them again.