455812 Search invoice number and convert XML to txt file

I have file "Bach" in XML, se attached, this is from card payments. Containg card payment for one day, it gives me the order number and ammount. I have file "Invoice-Order" This contains a lot of invoices (faktura) and Order (Order) number connected to this invoice and names (namn) This file is long and contains all invoices. The script/program shall search for the order number from batch in invoice-Order file and copy the invoice number in same row. It shall create file "Bankgiro inb" (name ending with the date as in attached) The only rows to change is date in top (20101030 in example)and the ones starting with 20 Last in first column it shall put invoice number as in example. And the amount (from xml file) to be put in exact same place in second column as in example. I want to be able to put many XML files in one folder, the script takes each xml file, searches for the invoice number in Invoice-Order file and crates the Bankgiro_inbet_date time file.