Note that I am not licensed to practice in your state.
I will answer your creditor question at the end of this post but I want you to consider another issue. If your SSDI is not sustaining you and you are now living off of credit cards, is this really a sustainable option for you? Instead of simply going with a debt counselor, you need to re-evaluate your whole living situation and standard of living.
Do you currently own a home? If so and if you stay in that home but can't afford to have the basics of living without using a credit card, perhaps it is time to sell the home and either downsize to a smaller one or start renting. This will free up money for you on a monthly, sustainable, basis.
If you don't own a home and you're already renting but still can't make ends meet - do you have children or relatives you can stay with instead? Have you taped into all state resources (ie: food stamps, other state income assistance)? Simply put, you need to find a good sustainable solution to your problem. Simply getting the creditors to stop calling is a short term solution to a long term problem.
What you should do with the creditors is this: When they call, answer them. Dodging creditors and collection agencies is no way to live. They will continue to call and call and call. Their job is to harrass until you pay so avoiding them is not an option if you want to remain sane. Pick up when they call and tell them:
"My only source of income is SSDI and I cannot pay. There is no money for me to pay right now and I will not promise to send you money nor will I actually send you money. Please stop calling. I will be sending a letter in accordance with the Fair Debt Collections Act to you and in accordance with the law, you must stop calling."
You then need to get their address and write them a letter stating exactly what you told them. Get the letter notarized if possible and send it certified mail to their address. Keep a copy of the receipt for future purposes. They should stop calling you after that point.
SSDI is exempt from the claims of creditors, but the proceeds of an inheritance probably is not. Depending on the amount of debt you have, it may make sense to file a Chapter 7 bankruptcy to discharge the debts. They will have to stop contacting you, and as long as the inheritance is not within a year after the discharge, it too should be safe.