Find ComboBox Value & Enter TextBox Into Corresponding Cell

I have a userform that has two comboboxes to search data on a sheet and a textbox to input data to a specific cell on the same sheet. The cell that the textbox writes to is determined by the combination of choices selected in the comboboxes. The comboboxes are searching as required but I don't know how to determine which cell to write my data from the textbox to. I'll attempt to clarify...combobox1(drivename) searches the data in column C, combobox2(unconformlist) searches the data in column H. The combination of these determines a specific row and I need to write data from the textbox(initials) into this row in column M.

Private Sub CancelButton_Click()
Unload Me
Sheets("Index").Select
End Sub

Private Sub initials_Change()
initials = UCase(initials)
End Sub

Private Sub OKButton_Click()
Dim ws As Worksheet
Set ws = Worksheets("QAQCconformity")...................