paying for a cellphone i am not in possession of !

Hi , I purchased a cellphone via mondo in 2021 October . i received two cellphones instead of one cellphone. To which i sent the one cellphone back . I have since been paying for a cellphone i am not in possession of. No one is willing to help i was sent from pillar to post and till now there has been no resolution or feedback- i even emailed *** . and she also has not gotten back to me .