Unfortunately, until the amount you owe the IRS hits zero, they can and will garnish your social security checks. Owed taxes and child support are the few things that can be garnished from social security checks.
SSA has regulations and guidelines they follow in these circumstances.
You could call or visit your local office to make sure the amount they are deducting is correct.
Your local office is located at 2660 Park Marina Drive, Suite A, Redding, CA 96001 (866-964-1236).
If there is one thing the IRS does well, it is flood you with paperwork. I bet you received many "you have a balance due" notice. I bet you received the "contact us or we will levy against your asset" notices. I suspect you "assumed" they couldn't touch your SSD, so you ignored it.
Generally, you don't get your money back from a recurring garnishment. You ask for the hardship levy release and non-collectable status to "stop" the garnishment, but you don't get the money back. Sorry.
I am not saying the IRS never screws this up, but the IRS letter generating process in the collection arena is nearly 100% automated.
Since contacting the normal IRS Office has not helped try contacting the 911 office. It is called the taxpayers advocate office. They should be able to help you to stop having your Social Security levied. During the interim stop having your Social Security funds deposited into that bank account. Transfer your social security deposit into another bank account. Or close that bank account. I don't need is not practical, but it will stop the IRS.
The above is not legal advice. It is an illustration of options that can be used in certain situations. I have not examined all of your facts, if I did I might provide a different response.