There's no need for the reference number. Most of the time you just need to submit copies of your ID, some utility / bank statement, and the denial letter.
The credit bureau will then take about 2-4 weeks to mail back a physical copy of your credit report.
Just note down the report number itself. That's what you need to monitor / dispute your credit file online. Other than that you can shred the physical copy. The report itself however will not include any credit scores.
And thanks for the compliments 