The OP is complaining that he did not receive a priority baggage tag, that priority baggage is a clearly advertised benefit on BA, and that this is stated on the website.
You are shifting the discussion that you and I were having.
Yes, you are correct in that there is no such published benefit, however at the same time a bag tag with "priority" written all over it is a pretty blatant piece of advertising and one that creates an expectation in the consumer that the airline is going to provide a specific service. As I said before, the continued use of these tags is misleading and they should probably be withdrawn.