American Express AMEX Not Honoring/Crediting 60,000 Skymiles Promotion marketed to me to open a Delta Gold Skymiles Card Nationwide

Cancelled my accounts with AMEX tonight after not receiving the promotional 60,000 miles from signing up with Delta Gold Skymiles card marketed directly to me. Customer service said they could do nothing to remedy and told me to take it up with Delta. Delta said it was an AMEX issue. I know closing my accounts won't be on AMEX's radar but I refuse to deal with companies out of principle that dupe their customers with false and misleading marketing and don't care to make things right. Very disappointed as I signed up to get the bonus and exclusively used the card to make the spend limit. I could have used another card for rewards and let an honest company make the fees on the transactions. Feel very mislead and upset.