Are you only installing one update or a bunch of them?
If you're doing more than one, try doing one at a time (download one, install it and cancel the rest). This will help eliminate corrupted downloads.
If you're doing only one, you can try two things, hard wire your modem/router to you ps3, that will give you a consistent connection or you can wait a while and try downloading later.
Most, if not all, the time you get 80029564 error code is due to corrupted downloads. This normally occurs during peak time when their servers are congested. You'll have to try at different times (say 2 hours apart) to find out when their servers clear. I don't know where you live so I can't give you a more accurate time to try downloading.
