We estimated the effort to accomplish our software enhancement on the basis of the original feature working as designed. When testing we found it had significant defects and did not work as designed. We rolled back all our changes and proved the original code had these defects at release. The original team claimed otherwise despite us proving it on unaltered code.
We found the source of the defects but are not allowed to remove it. Instead we have had to absorb fixing all the affected features (well beyond the original scope of our story) and now are being asked to test all the old features.
The scope of the testing is enormous. How do get the other teams to help test their original work again. They all claim its nothing to do with them despite us proving the functionality didnt work in the released version of the code.