Dynamic range in SUMIFS

Hi Guys,

I'm new to this forum, but hopefully I'm posting things in the correct format. I'm having an issue with inserting a dynamic range into the SUMIFS function.

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What I have is basically an exported Excel sheet of data from my office's system, which I need to process. I just want to see every collector's total collection for each week.

This is the how I'm trying to get the final report to look like:

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The SUMIFS function works, but the range has been manually set by my. The number of rows in the data sheet will be different every month, so what I need to do is to have the range dynamic, but I've been unable to do so.

I'm using the following function to find the row (but without the alphabet) after the end of a collector:
=MATCH("total for aliza :",$A:$A,0)

and the following function to find the row before the start of the collector's data:
=MATCH("aliza :",$A:$A,0)

I've been experimenting with INDEX, OFFSET, and a few other functions, but I haven't been able to get it right, with the OFFSET function being something that I'm struggling with.

Any help on this would be greatly appreciated.

The data I'm trying to process has been highlighted in green. I've also attached the Excel sheet here, in case it helps.

Thanks!