I am so angry that Prudential can get away with this

I have been fighting for quite sometime with Prudential long term disability that I have been paying for the last 11 year of being with my company. I have been in the hospital several times do to stress in fighting with them all of the time to get another check. It is always the same. We are reviewing your records at this present time and will be in contact with you soon. I was supposed to receive one more check for the month of November and was given a letter from them saying that they have over paid me in the amount close to 6k. I am extremely furious that they have the gall to do this to me. They have given me bleeding ulcers and have been put in the hospital at one point due to a rep from prudential coming to see me at my hospital bed. I was so angry at how I have been treated by the rep, that I opened up my mouth and told her that maybe I should just open up my own abdomen to show you the debilitating disease I have that will eventually kill me. I know that my years are not very long. But how can a billion dollar company get away with this?