I had a similar experience with a SaaS. They let us run fine for months, then started degrading our service. When we contacted them, they tried to convince us

I had a similar experience with a SaaS. They let us run fine for months, then started degrading our service. When we contacted them, they tried to convince us we had a bug in our implementation. No, we confirmed we were using their service exactly as we intended to. They seemed to have designed their service with a particular use case in mind, and ours wasn't it. We tried multiple times to explain our use case and why their service was useful for us, because we didn't want them to think we were using the service in bad faith, but if they understood, they never let on. After much grumbling, they would lift the restrictions on us, but apparently not far, because we'd run into them again weeks or months later as our traffic increased. They were obviously unhappy with the way we were using their service and determined to cause issues for us, so we gave up and stopped using them.