Help to check I have billed correctly

Hi there, I need some support with some PO's and timesheets I have done. I'm not sure if I have missed any and I could do with someone going through the documents to make sure I haven't At the moment I receive PO's from my client and I manually add the time, for example they could send a PO which is 250$ but each of the work I do is in segments, so I usually add the time as $50 (for example) then the following week if I done 2 hours I will add ($100) - We technically add the amount (portion by portion) of the PO until I've fully got the PO amount Now the issue I have is that I have received multiple PO's and also have been adding time as I go along but I can't help but think that I forgot to add some time as I've done quite a lot of different sessions. Would you be ever so kind to help with the request? I have 31 PO's I need the person to check They need to check if each PO has been successfully billed and then any that have not been billed yet or some that have incorrectly been billed (if you notice a PO has had too much time on the project) I have the manual time input screenshots, PO's I received from the client and need to check both This will involve someone good with some Maths and very high attention to detail to be able to just tell me e.g. you have billed 20 correctly, 5 are overbilled, 3 haven't been billed yet, 10 projects are still to come. Some of the projects are later in the year so they are intentionally left blank. I could do with someone taking ownership, setting up an excel or word doc to show me at the end Thanks