Monthly sheet FBA fees issue

Hello
I had enrolled a product for SNL program and it falls under the category of standard envelop and shows 0.86GBP for FBA Fee. This fee is reflecting on my seller central as well till now.

After selling an item whole month of November, I downloaded monthly report to calculate profit but surprized to see Amazon has deducted standard FBA fee which was 1.71GBP before SNL.

I have opened a case with amazon support but they are only educating me about there SNL threshold policy but can’t resolve this problem.

I need your valuable suggestions in this regard.

Thanks