What can I tell my bank for a dispute/chargeback after a failed refund

[smunky]

I used refunding services to try to get a new phone but the refund was unsuccessful. The vendor I purchased from banned my account and now i’m stuck with the phone and can’t return it. I wanna try getting a chargeback with my bank but i’m not sure what to tell them that’ll sound believable. Does anyone have any ideas or suggestions?