It also depends on how credit card savvy the salesperson is. If you know your floor limit (your declared statement with the processor about your average charge), you know you are going over it, and you contact your processor preemptively with your documentation and issues, it will make the override work better.

For example, I took a very large phone charge and I faxed the contract, some identification from the person making the charge, and a pencilled impression of the card to the credit card company and they allowed a charge of more than 10 times our stated limit. In an age of identity theft, people get nervous and feel put out doing this, but you can do this.

On the flip side, when I was buying an $800 unlocked phone in Dubai with a US credit, I called my credit card company, verified my identity, and told them what I was about to do. No problem. The only thing that bugged me was that I didn't have enough Dhms on my prepaid phone to make the call and had to use my ATT to complete it. Ugh.