benefits from purchasing the foreign debt (credit card individual bad debt)

Hello everyone,
I am curious about the potential benefits from purchasing the foreign debt (credit card individual bad debt) for individual person or a company. Would that be possible to write off this bad debt and cut the base of income tax? As an example the Germany based person purchase will buy distressed UK individual credit card debt and after sometime announce it as doubtful debt and make write off.
I would be grateful for all advices.
Regards