Earlier Year Update

I had a conversation with HMRC today as the figure they received as PAYE owing for Month 12 were incorrect. They said I need to submit an Earlier year update for each employee but this is showing as zero adjustments.

The issue was that I only started running this payroll in month 12 and I think that the figures that then transmitted to HMRC were correct for PAYE for that month but it looks like the national insurance was accumulative.

Anybody else had this problem and how do I rectify as debt collectors keep turning up at my client's premises.