If a software company installs an app that ''integrates'' with another app, and then doesn''t return phone calls, can you charge them for removing app?

They were going to give us a quote for their services... but they never did. Now they won''t return our emails or phone calls and we are unsure what their application does. We would like to have it removed, and we don''t trust them to remove it (although they have never offered). Can we have a third party remove it, verify the integrity of the existing app...and collect the removal fee from them? We do know that tampering with someones digital property has consequences...