Started with Dedicated IP and then swapped without any notification

Upon establishing a new account, we were assured eligibility for a dedicated IP based on our account size. With this expectation, we engaged in a comprehensive six-week IP warming phase with the guidance of an onboarding specialist. However, after two months, a troubling pattern emerged: our emails consistently landed in spam. Perplexed by this, we conducted further investigation, only to be informed by customer service that, contrary to our initial understanding and without prior notice, our emails were being sent from a shared IP.

This revelation was both unexpected and disappointing, as it starkly contrasted with the initial commitments made to us. 

Has anyone here encountered a similar sudden shift in IP assignments for their account? I'm curious about the potential reasons behind such changes.

I appreciate any insights or shared experiences you might have regarding navigating these types of service discrepancies.