I'm almost certain I got the number almost immediately. It took awhile for some of the companies to recognize it because they had to update their databases and it wasn't instantaneous but I don't remember having to wait to get the number itself.
This may sound dumb but ... you took the test? you passed? Or do you not have your results yet? Just wondering if maybe you were under the impression that paying the fee got you the number. Paying the fee should get you the access to the test. You have to pass the test to get the number.
Time to build a bigger bridge.