I'm trying to sums up the total for different vendors with mulitple entries,
but I have payments and invoice amounts in the same column. I only want to
add up invoices. My data looks like this, I think I need a count if function
I think but i can't get it to work.

Col b Col D Col G (£) Col I
Access Invoice 500 Sum up only invoice
Amounts leaving out
Access Payment 500 Payment value
Acesss Invoice 400
Argosy Invoice 300
Argosy Payment 300

Is is Count If or sum if ?
Any assistance would be appreciated
Thank You