I need to output customer number on the CSV export file i.e the number shown in brackets in the attached screenshot. I cannot find any language constant that does the job.

I need this because the PayPal transaction record contains this number and I can use it to match and confirm the payment status of bookings. I have discovered that customers sometimes use other someone else's account for payment, have different surnames (maybe they've married/divorced/changed there name for some reason between registering their PayPal account) or have used a different email address. Essentially, I need a common key to batch Matukio Booking Records and PayPal transaction records.

Kind regards
Neil