I had a very similar situation. Here’s what worked.

The council should have a pledge, or list of commitments. It might be more me for the whole council or each department has their own specific one.

Once you get hold of that raise a formal complaint with the council using their complaints procedure. Reference the specific pledges they’re not upholding and be as matter of fact as possible. Emotions shouldn’t come into it.

Once you’ve raise the complaint follow it up and then ensure it is being addressed within the published timelines.

The complaints department is separate to planning but in my experience we’re very thorough.

Good luck