Hi there, sorry for the poor title, not quite too sure what to call this one.

I extract roughly 300 lines of data from our customer complaints database each month that I need to do some manual fault finding and sorting of before I can generate graphs and charts. I usually do this towards the end of the month to allow as much detail to be entered in these cases. (The details are updated multiple times before being closed). I would like to be able to extract the data on a weekly basis and complete the manual data entry on the cases that I know what the issue is (columns F & G). The next week I would pull the same data and if the case number is a match, the new extracted data would overwrite the previous weeks entries (columns A to E) but leave the manually entered data in columns F & G.

For example, in week 1 of September I have 4 customer complaints. I extract this from the database, copy to my master sheet and manually enter the root cause of the two entries I have the data for:
Week 1.jpg

In week 2 of September, I have a total of 6 customer complaints. I extract these from the database and want to copy them to the master sheet. What I would like to do is overwrite the previous week's data in columns A to E with the new data while leaving columns F and G untouched. I need to make sure that the lines that are copied over are the same so I would like to use the 'Case No' data in column B as a lookup to make sure the data being copied over is for the correct case.
Week 2.jpg

Any help here would be greatly appreciated.