Buying property that doesn't belong to me

I bought a farm /property in 2012. Every thing went well. After 7 years that I stayed there I had to find out that the property doesn't belong to me. When contacted the bank, after a long struggle they have send out there head assessor. He comfirmed that they made a huge mistake. Today it's now more than a year that I still struggle to sort this out. Can't buy an other property because bond is still on my name for a property that I don't own. What can I do to sort this