Chase increased sign up bonus right after I was approved for card

I applied and was approved for IHG Premier with annual fee and the very next day the offer increased from 140k to 300k. I called immediately and customer service said I could have the new offer applied and it was annotated on my account. I met the sign up bonus and they refuse to apply the 300k offer. I’ve sent over 20 messages showing documentation and contact dates showing I should be eligible and that they had promised. I have now threatened to report to CFPB, because I don’t know what else to do, what else can I do or am I SOL?