Settlement date meaningless?

Back in September I "bought" a certain number of Pibs through my SIPP broker. Interest was due on February 27th this year but did not appear in my account. To cut a long story short, it turns out that the stock was not delivered because of a "shortage of stock" (even though it has appeared in my account ever since dealing date). I have been assured that "electronically" I am the beneficial owner of these Pibs but until they are physically delivered, they cannot be registered with the Company and therefore my interest will not be credited. When the stock is finally delivered and registered I will receive interest, could be next week, next month or next year, who knows? However, my account was debited on settlement date (funny ol' world). I am told this is "common practice" but would appreciate any thoughts from you guys. Nick