Such jobs are my daily practice. I plan to complete the project via writing an Excel macro contained in a separate XLSM file.
This approach makes further use of the macro very convenient by offering a Control sheet containing cells populated by the usual Open file and/or select folder dialogs to identify the current input and output files and hosting command buttons and other controls if necessary. In my approach you'll have opportunity to consult details with me, to test pilot solutions if necessary in order to achieve an optimal final solution. Further use of macros, fixing of bugs and minor changes are included in the bid without any additional fees.
Regards!