And then one more of that ongoing list of phone calls brought the somewhat off the cuff remark: "oh, didn't we tell you the server's address was changed?". Well no, they hadn't told us. We'd been told of password changes and various technical difficulties that might be causing the problem, but nobody had told us the all-important information that if you want to transfer files to the server you have to use a different address.
Now we know, and this is actually posted on the date given.