I have reference numbers in column `H`

and status of repair in column `R`

(yes or no).

I am trying to count the unique reference numbers in column `H`

only if column `R`

is `No`

.

I currently have the formula `=SUM(- -(Frequency(H2:H58,H2:H58)>0))`

, which provides me with a count of the unique reference number. However, can you advise me how to update this to count unique reference numbers in `H2:H58`

only if `R2:R58 = No`