Ah yes, the magic words “I will file a complaint with the relevant regulatory agencies” really do grease the wheels with data privacy requests.
Magically “there’s really not much we can do because our customer is the one who owns your data” becomes “we have initiated a deletion of your records within our customer’s account and have started an investigation into possible violations of our Acceptable Use Policy”.
Never hesitate to shake the branch when dealing with corporations. In Europe, California, and a growing list of other places you have an absolute right to control your personal data.