IRS saying I owe them money from previous debt after filing an amended return. and I already paid that debt, HELP!

I owed the IRS money from 2009 and 2010($2,500). I set up a payment plan in 2014. When I filed my 2014 return they kept all of it, and when I filed for 2015 they kept the rest of my debt and I received the remaining amount on my return. Recently I discovered the tax preparer had filed me and my wife's 2014 and 2015 tax returns as single. I went to a CPA to get that corrected knowing that we may owe taxes. When the CPA file the amended return he showed us that the IRS owed us money. Last week I received 2 letters from IRS, one was a statement saying I owe them nothing form my payment plan, the other one it was from my amended return saying we owe them $3,000 "from a previous debt "we" had". How can this be????? I already paid my debt, they took what I owed from my 2015 return, how can this be??? I don't care If I don't receive any money, but owing them from a "debt" that even they sent a letter saying I owe $0.. Im confused.....???????

I owed the IRS money from 2009 and 2010($2,500). I set up a payment plan in 2014. When I filed my 2014 return they kept all of it, and when I filed for 2015 they kept the rest of my debt and I received the remaining amount on my return. Recently I discovered the tax preparer had filed me and my wife's 2014 and 2015 tax returns as single. I went to a CPA to get that corrected knowing that we may owe taxes. When the CPA file the amended return he showed us that the IRS owed us money. Last week I received 2 letters from IRS, one was a statement saying I owe them nothing form my payment plan, the other one it was from my amended return saying we owe them $3,000 "from a previous debt "we" had". How can this be?????==> Sometimes, the IRS errors are ridiculous.
Do not pack if you receive a letter from the IRS; Most contact from the IRS is triggered by minor issues or common errors and there are plenty of ?em. The biggest reason that people receive letters from the IRS is human error. Several
years ago, a taxpayer making less than $19K requested a refund of $513. Instead, he received a letter from the IRS demanding payment of more than $300 M.. An IRS official later confirmed that about 3,000 people around the nation got similar erroneous notices. An audit is merely a process where the IRS asks you to substantiate the numbers on your tax return.As you
know what the IRS wants, please all your tax professional filing all the returns for you.
I already paid my debt, they took what I owed from my 2015 return, how can this be???==>As mentioned previously, please contact yur tax preparer for more detail. Almost all of the letters that you receive from the IRS or your state are computer-generated. This means that if an input error was made, it?s now your problem. But in almost all cases, a well-drafted letter with appropriate substantiation will win the day.

I don't care If I don't receive any money, but owing them from a "debt" that even they sent a letter saying I owe $0.. Im confused.....???????=>as said you can let your tax preparer contact the IRS for more detail.