Penny... we had this exact situation.

We opened a new selling ID after we had two other long established selling IDs (one of them 10-years old) with no problems whatsoever.

They held funds on the new ID once it made sales.

I called them and explained that we have a good track record on two other selling IDs but they refused to lift the hold. We use regular mail so I had no tracking to show them.

So I submitted a complaint to the FOS citing our other long term accounts.

Within 48-hours the holds were magically released and they have never held a single cent on that ID ever since.

So I would recommend going the FOS route if they won't comply. It's a pretty simple online form to fill in.