Error when closing Service Call

Error message is occuring when trying to close / update a service call.

'No related record found [Service Calls - Contact Person] [Message 60156-18]

and

'Removing activites from service call not allowed'

Some history to the BP which may be linked

1 business partner was created

2 service messages and activities where created

3. Bp was accidently deleted

4. BP was reinstated

5. Old service messages have error when closing

Any solutions on how to update the service call - so it can be closed?