Clarification of Terms: The only true fee from each card brand is the percentage charge applied to volume.
The various other fees such as network access, foreign handling, and so forth are charges incurred through processing behavior at the individual transaction level.
Keep in mind that many factors contribute to the markup, so not everything will be negotiable, or it will only be negotiable to a point. it's split among all of the organizations that facilitate the processing of your business's transactions such as the acquiring bank, processor, ISO(s), gateway or software provider and others.
The markup must cover cost as well as profit for all of these entities.
Interchange plus allows for interchange credits on refunded transactions.
Credit card processing fees aren't as confusing as you might think.