Can I use donor sperm from a donor who is permanently blocked?

Yes, if you already have a donor-conceived child with sperm from this donor.  

If our Genetics team assesses that a reported condition might be related to the use of sperm from this donor, the donor will be permanently blocked. Donor sperm from permanently blocked donors is only accessible to you if you have already conceived a child with sperm from this donor and wish for a genetic sibling.

If you want to buy sperm from a permanently blocked donor, you must therefore declare that you already have a child with this sperm donor, and that you have received and understood the information concerning the registered disease.