I do agree with you in respect thatthe experience is not unique, but I argue it is the customers right to call as much as they like to try and get what they want. As we all know availability can come and go at odd times and ways.
Anyway just my 2 cents.
Yes. If something can't be resolved or is too hard to resolve on the website. By all means, call till you get what you want. But a NB calling to get a call centre to release Z fare buckets is pointless, unless its a technical error where you see the fare but can't book (Happy to be proven wrong). I don't even pester VA for releasing fares for my upgrades, I just wait and cop Y if I don't get it.