Removing data from columns in tabs without disrupting formulas (currently displaying #N/A)

Hi Guru’s,

I need some assistance with my spreadsheet. It’s been created, however I need to have a blank document for future use.
Column C follows the key/legend on the right. When you input one of the 4 codes, it automatically updates column E with the cost of the service.
The tabs below (highlighted in green), have had data in them, however, when I remove the data from column C, impacts both columns E & F and displays as “#N/A”. This impacts the dashboard on the FY Totals tab.
Could someone please help me ?
For convenience, I’ve included the spreadsheet.
Thanks,

QM.