This error message suggests that there is a problem with the request that is being sent to the API. “Error retrieving ‘completions’: 400 Bad Request” typically indicates that the API is unable to process the request due to an issue with the syntax or structure of the request.
A common reason of the error 400 is that the prompt exceed the limit of character allowed by the API.
I recommend you check the API documentation to see if there are any limits on the size of the prompt or the number of items in the question. If there are limits, they should make sure that the prompt they are sending meets those requirements.
Also, you can try rephrasing the question and make sure that the prompt is in a clear and structured format. This way, they might be able to determine if the issue is with the question or with the underlying service.