Start with the support route linked to your booking, policy administration, or document issue process. If you have the certificate already, use the same details when writing so support can find the file more easily.
Be specific about what you need. Asking for “my documents” is less helpful than asking for “my certificate of insurance and policy wording” or “proof of cover for my provider”. Specific requests usually move faster.
If your request relates to a correction or a mismatch, mention exactly which detail is wrong and where it appears. That saves time.