Short answer
You can propose a higher payment directly in the app, under the actions menu, if it turns out the task requires more work than ad suggested.
You do this before continuing the task.
The advertiser chooses to accept or reject the proposal.
Details – step by step
Open the Actions menu.
Select Propose new payment.
Write a short reason for the higher payment.
Add photos showing the extra work.
Set the new price and submit.
Wait for the advertiser’s response.
What happens next
If the advertiser accepts, the payment is updated.
You continue the task and get paid the new amount.
If the advertiser rejects, you are deselected from the ad.
The ad is published again and your rating is not affected.
Good to know
You can edit or withdraw the proposal before a decision.
You cannot continue the task until the proposal is handled.
The feature is only available on iOS and for credit card paid ads.