Unfair blacklisted

I had a phone with payjoy (oppo,of which I returned t within a week @edgars cape gate)I closed the account leaving no arrears,phone was accepted!@Edgar's cape gate (.to my surprise after 3/4months iam getting calls from debt collectors about the same phone I returned,I then I went Edgar's and the lady who was helping said it's payjoy who ddnt fetch the phone,so I called payjoy was told thy wl come fetch t,then on following day I went 2check if thy sent t or someone fetched t as I was promised on th call,and surprisingly the phone s still there and I called again payjoy ,now new information I was told(the lady who was helping me ddnt send my details according 2their process,and the lady was apparently absent from work and because of tht no one cam help me,and payjoy sent my name to credit burae for the phone I brought back within a week around September. Very pathetic and *********** service especially from payjoy@ Edgar's cape gate ,no customer care from tht lady.iam currently taking this up with my legal team as it is tarnishing my credit history