The store keeps a share and the rest is refunded to you.
7% by default. A seller can set it as high as 20% and no higher. For anything that spoils while it waits — food, flowers, anything with a life — it is a flat 20%.
Whatever they chose was shown to you before you bid.
Why there is a charge at all
Because somebody stopped working, wrapped the thing, and kept it aside for three days while you did not come. That is real time and real shelf space, and for a baker it is a cake nobody can now buy.
It is not a punishment for changing your mind. It is the cost of the arrangement you agreed to.
If you are going to be late
Talk to the seller before the deadline. Most will be flexible if asked; none are obliged to be, and none can be if they have already thrown it away.
Questions people ask
How long do I actually have?
72 hours by default, from when the seller marks it ready. The listing states theirs.
When was I told about the fee?
Before you bid. Pickup terms are agreed at that point, not at checkout — which is the whole design.
Do I get the delivery charge back?
There is no delivery charge on a collect-only item.
What if I could not collect for a genuine reason?
Tell the seller. If you think the charge is wrong, raise it.
More: collecting in person.