I recently completed a dna test as I have always been unsure as to weather I am the biological father of a 5yr old and my ex hasn't allowed me to see him for the last 3yrs the results came back and I am not the biological father however I have been paying csa straight from my wages for 5yrs I need to know how I stop this payment and also more impotantly if Im entitled to claim the money I have so far paid in maintenance back?

You file a petition with the court that issued the original support order to end the support order. If the DNA test was ordered by the court, then you already have a case pending. If not, you need to file and the court may order its own test.

It is unlikely you can get anything back. For the court to have ordered support, you had to acknowledge paternity. In fact, depending on the laws where you live (ANY question on law needs to include your general locale as laws vary by area.) you may not even be able to stop payments as the time window for you to protest paternity may have closed.

Do you have an attorney? If not, I would get one.

I recently completed a dna test as i have always been unsure as to weather I am the biological father of a 5yr old and my ex hasnt allowed me to see him for the last 3yrs the results came back and i am not the biological father however i have been paying csa straight from my wages for 5yrs i need to know how I stop this payment and also more impotantly if Im entitled to claim the money I have so far paid in maintainance back?

It depends on which state has jurisdiction over the case. Some states allow child support to be stopped, other states would apply "Estoppel"/ you have been paying then you will have to pay in the future,too/