I have sent an invoice with the correct amount when customer whats to payt it is more how do I fix t

can any one help i have sent an invoice with the correct amount of postage and when the customner goes to pay palk it more ???

Did you hit 'recalculate'? That is 'revert to original'. Put the correct postage cost in, DON't hit recalculate, and send to the buyer. Check 'preview' to make sure.

Is the customer using a mobile app? They won't see combined invoices unless they do it on a browser (mobile full site or PC computer).