Sounds like a management issue. Make sure whoever leads them is making clear requests (who is responsible for the task, what is the task, how is completion of t

Sounds like a management issue. Make sure whoever leads them is making clear requests (who is responsible for the task, what is the task, how is completion of the task measured, when should the task be finished) and that will give you a framework for communicating expectations and you can measure performance on it. The developers can negotiate the timing of it - but always make sure they give you specifics, "I can have that done by Friday at 5pm". It's a simple thing to do, but leads to powerful results.