Paying for a phone i dont know

Around july they was a phone which was deliver by MTN at my work place and i told them i did not order any phone and they should take it back with them which they did they i called to try and understand what was happening and to make sure that i did not order any phone

Then now i am being debited for the same phone i did not order and a phone i am not using when i call i am being told to call with a MTN number i don't have a MTN number,

i used a friends phone to call they was told to make an affidavit and send but the reply i am getting is still to send an affidavit after i have sent it.

Can they please stop debiting me for something i don't know please