Some additional info and updates to the api and api docs would be great.
changing "organisationId" to "orgid" would avoid the spelling issue as well as capitalization mistakes.
Use Lowercase Letters:
Whenever possible, use lowercase letters in your API URLs. This is mainly because the RFC 3986 Specification For URI Standards denotes that URIs are case-sensitive (except for the scheme and host components of the URL). Lowercase letters for URIs are in widespread use, and also help avoid confusion about inconsistent capitalization. If you add capital letters, you should be aware that this will cause confusion and result in user error more often than not.