Amazon UK Bookkeeping help?

Hello! I am running my self around the wall with this one. In the UK I am VAT registered and happy with all my books etc until they changed all the invoices or so in august.

Let me clear up where I’m lost, I use the monthly summary to input a journal entry of all my different costs and until august al the invoices always matched up and it was fine! However now the amount I am being invoices for is significantly higher than what is on the monthly summary, which one do I use?

For example the refunded fees invoices I can find a match for those quite easily on the monthly and see right they all add up to that there’s that refund. But the FBA and seller fees have been all over the place with the monthly statement showing around 1.5k for seller fees for example and then I get an invoice for around 2.1k it’d be fine if I can just find where they get this 2.1 from and how to fit it in to the monthly!