Amex/Collect Corp settlement

I had a settlement letter faxed today from Collect corp that was agreed upon today. The only thing that concerns me is they verbally said I could pay via the Amex web site, however on the settlement letter is says to send them the money.

They state is is a standard form letter for Amex accounts, I will try to confirm this with Amex but just wanted some opinions.

They did offer to take check by phone, but I feel more comfortable paying via Amex's site.

Thanks