Could you please correct me? it is an email

Thank you for your GT payment certificate. It has come to my attention that your final invoice was not itemized properly. I am attaching a corrected invoice for your records to show material cost as well as labour. There is no additional charge to you. Thank you very much.

Can I correct it and send you invoice to show you how much we have spend to buy materials and how much we spend for labour cost? [-- It sounds like this is something you are required to send, so I would just send it. Your message should explain that it is a corrected invoice and not additional payment due]

As a subcontractor we should be charge 20% CIS only from labour cost not included materials so that's why we would like to make it more clear for you. [-- I left this out because the itemized invoice should explain everything, unless there is a particular reason your customer needs to know your company's accounting structure.]

I made a lot of changes because business correspondence is generally a little more formal in English. Write only what needs to be said, in a polite and professional manner. Sorry if my explanations are complicated; I hope you can understand!