Discovery not coverering a patient for life threatening situations

I am very disappointing in discovery. We took my mother to ER late one night because of an piece of food stuck in her throat. She could not swallow anything including saliva. She is 72 years old and are on one of the highest plans on discovery. Discovery refused to pay for for the endoscopy. So what they are saying is they will not pay for life threatening situations on one of the highest plans?. You can only survive 3 days without water. No excuse from discovery. I would like an agent from discovery to call me asap and clear this up. This is absolutely ridiculous. I will not leave it like this and i will fight them every single day until they pay. They also have problems with chronic conditions.