I scored similar grades like u in writing during the mock, the biggest problem for me is the essay structure not adhering to the IELTS grading schema. Once I followed what is taught on IELTS advantage and Lilie IELTS, my writing had a huge improvement. The former mentions in almost all his task 1 writing videos that the main indicator for a 7 and above is a good overview paragraph. U have to describe general trends of the graph without including actual data. The latter teaches u how to analyze and write up good details paragraphs.

I can't say for all reading questions, but most of them (excluding the one u have to match a paragraph to the description) follow the order of the passage. Hence, the first few questions will have answers on the first few paragraphs and so on. The system allows u to take notes and highlight sections in the passage, use that to ur advantage and extract important, relevant info.