SAAS needs my foreign partners birth certificate and she can't get it, HowDoWeGetIt?

My partner is a UK citizen and was born in Amsterdam. She has lived in the UK since she was 2 and now she needs to apply for SAAS. She is 23 years old and hasn't spoken to her mother in years (won't go into it, no contact) and her father lives in Amsterdam and has no contact with her.

The SAAS application is asking for her "Birth District" from her birth certificate. She doesn't have a copy of it. We've tried so, so hard, to find out how to request it from the Netherlands but we can't find one single resource on how to get a copy of it. SAAS won't let her proceed with the online application until we enter it.

Does anybody know what we can do or if SAAS can do anything about it?