I guess a closer analogy would be rental storage. If you don’t pay your mini storage bill, in some regions the landlord will confiscate your property, holding it hostage until you pay. And if that fails, they’ll even auction off your contents.
So in the case at hand the creditor is holding the debtor’s data hostage. One difference is that the data has no value to the creditor and is not in the creditor’s possession. It would be interesting to know if the contracts in place legally designate the data as the creditor’s property. If not, the data remains the property of the consumer.
This is covered by human rights law. Universal Declaration of Human Rights, Article 17 ¶2:
“No one shall be arbitrarily deprived of his property.”
If the phone user did not sign off on repossession of their data, and thus the data remains their property, then the above-quoted human right is violated in the OP’s scenario.