I'm a bit annoyed with my current SPG Amex credit limit. It's in the low thousands, while my other 4 credit cards (all Visas) have an average limit of 5x that, the highest of them having almost 10x as much...

Whenever I call and request for an increase, all the rep does is send me to some automated application... I did the automated application a few months ago and nothing happened. When I tell the rep that I want to talk to a human about it, they sound pretty confused and don't really know what to do (maybe I was just unlucky).

I want to use my SPG Amex as my primary card but I can't with such a low credit limit. I have to pay it quite often and it's getting annoying.

Is there a way to 'transfer' a credit line or at least use my high credit line elsewhere to argue that I'm creditworthy to them? Who should I talk to? Any other advice?

Thanks!