While I have no experience building software teams, I did navigate a few situations where a relationship between a business and a software vendor went sour. How

While I have no experience building software teams, I did navigate a few situations where a relationship between a business and a software vendor went sour. How long two parties can talk past each other is impressive sometimes. Once everyone is on the same page, seemingly insurmountable problems go away faster than you think. No matter what you decide, it sounds like in the short term there's no getting away from them. As such, I would attempt to open a dialog focussed on mutual success. If this is a niche, chances are you are as important to them as they are to you. Show genuine interest in the problems they are facing, rather than expressing frustration. Are they struggling in general? Perhaps there are ways to help them get back up to speed. What about you as a customer (e.g., too distinct a workflow) makes things extra complicated? Look for specific points of friction, and how to address those. A viable option, at least to get started, could be to use them as a building block. For example, handling that data exchange you mentioned. Establish a simplified format that is still detailed enough for them to do what they need. Then have your own logic, however complex, construct the input to their system. Add something in the opposite direction as well. Over time, you'll have more and more components that are easier to replace, because of their limited scope. Finding another vendor or building more custom solutions won't be all or nothing anymore, which is exactly where you want to be. Doing this in-house? I feel the challenges are already plentiful without that. Instead, lean more to the side of having a couple subject matter experts interact with a small(ish) software house. It wouldn't be the first time that eventually one of theirs jumps ship, tagging on a colleague or someone else from their network. Basically the team would build itself, organically. On a final note, I just wanted to say this sort of stuff fascinates me. Likely you wouldn't have time for anything like that, but I'd love to see in detail what your business is doing, and how said software is holding you back.