We are in California so it may be different where you are. I called the California Department of Insurance (our State Insurance Commissioner) which I found using this map:
http://www.naic.org/state_web_map.htmI gave your story (as much as I knew from your post.)
The commissioners office said that a company can require a 6 month to a year waiting period (depends on the size of the company you're at, ie, number of employees) - however - if you had no lapse in your group plan there's something called a "credible coverage period" which would be applied to that wait period, since you had continuous coverage. Try mentioning this to the insurance provider.
Depending on the type of insurance (PPO, HMO or indemnity plan) there may be a different agency that regulates health insurers.
You should contact your state agency and file a "request for assistance" or a complaint, depending on what they require.
In California there is the Department of Insurance and the Department of Managed Health Care. You should have similar agencies to assist you.
In the meantime you definitely should file for Medicare. Call your local office to ask about what they require. Be sure to mention ESRD.
If for reason you cannot get anywhere with your state commission or Medicare, there's probably a similar plan like this one that you may qualify for:
Major Risk Medical Insurance Program (MRMIP) - This program provides comprehensive health insurance for Californians who are unable to obtain coverage in the individual health insurance market. People enroll in the program because they have been rejected for coverage by an insurance company or health plan due to a pre-existing condition.
Don't give up - this is worth fighting for! Good luck!