Unresolved Account query

I have paid up my account March 2020', after that just around April 2020 i started receiving messages from them that i am owing them i asked for statements as to what i am owing i found out that i owe gadget insurance of R53.00, cell c airtime. subscription of R78 .00 , mobile vault subs R49 which i never hadand know nothing about these contracts and compkained several times upto date tobtrack for me and check who is benefitting from this as i am not using cell c network. I was promised that they will enquire. Last year around May i received a sms saying these insurance is cancelled and given the Ref; EDC *** and tge refund Ref; EDRF:210511- *** ,but upto date i still receive threatening messages that i must pay