If you are in an IVA any offer has to go through your IVA company.
IVA started March 2011, Completed March 2016 and certificate issued 11 days after final payment. It was not always easy but then some of the best decisions aren't.
As said, any settlement offer has to go through the IVA, which, if accepted, will bring it to a conclusion. Even if finished early, one way or another, the IVA will remain on your credit files for the full 6 years from the start date.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014