My MasterCard has been being a douche recently too.
Turns out I reached the limit
This is why Amex>all
Not really, if you hold an Amex Chargecard then the likelyhood is any request to your Mastercard provider about a new limit will met with 'certainly sir' anyway. Besides, 'No prescribed limit' on Amex doesn't mean you can pop off and order a lear jet no questions asked either.