Comment by wkat4242

And the combination of contacts are also unique enough to identify you. Even though they change over time. Some fuzzy matching, take in another few bits of fingerprint like device type and country and voila no advertiser ID required.

Ps smart idea to use it for that purpose. If I failed to get proper service I'd just review bomb the company everywhere and soon enough I'd get a call fixing my problem and asking to remove them :)