what case can be filled for employer who charge than they should ?

hi my employer  did not pay me separation because i resigned hence my case is still currently on nlrc, with constructive illegal dismissal non paymnent , illegal deduction and moral and exemplery damages  non coe issuance  , they admit through their lawyer and with signed documents from nlrc that they have a mistake on their calculation , they ask me to settle an overpayment salary  of 17800 and issued 2 letters of notice that i have to pay that sum , during our hearing at nlrc theyd  admit that the payroll calculation was wrong and and it suppose to  be only 13600 , they hold my coe until today what case i suppose to add on my complaint because  i already have documented proof of the incompetency of their bank to calculate  the right amount that i suppose to be in in debt , before they showed their mistake on payroll they agreed to issue my coe w accountabilities but after we talked today to our hearing they ask me to pay first the due  and will issue the coe , so i pursue my case to the next level and will ask for  PAO assistance on our next hearing on sept 28  to submit our position papers

I don't get the story, it seems that this is already in nlrc and you want to court and ask what additional charges that you can file? over a COE?

Utang mo yan.
Bayaran muna.

Parang sa tindahan, bayaran muna ang dapat bago ka bigyan ng resibo.

Pwede naman silang magbigay ng COE, pero pwede pa rin nakalagay na may utang ka pa sa kanila.

Kung bank ang may problema, bakit hindi yun ang habulin mo?

Inayos naman ng company ang computation. Nabayaran mo na ba yung 13600?