I have the lowest credit limit that I ever had on any of my cards (3000 only) on my SPG amex business card. CSR refused to increase the limit but suggested to apply for another amex green or gold card without the annual fee for the first year where there is no credit limit. What I usually do is when ever I expect to cross the credit limit, I overpay that month many times my credit limit, spend as much as I want and everyone is happy.