if it was a fixed figure, then you may be required to pay for all, regardless of what was used.
We've just sold our PPOR. it was a fixed advertising cost of around $650, which was obviously subsidised. I expect that we will need to pay that full amount despite it selling in less than a week.
Even though it sold quickly, most of the items included in the amount were already done, eg photos, floor plan etc.
After having another property (different agent) on the market for several months, where the advertising fees were over $10 000, and the property still hasnt sold... we're more than happy to pay the full amount for this one,