very bad bad service ,and i am a very unhappy customer

i write to complain on the 3*6/2017 and then again on the 7/6/2019 since i had no feedback ,i got automatic replies and refences: I explain in the email that i was sold a cellphone telephonic and received the cellphone around the 16,17 April 2019 and i was shock to find out it was not the phone i wanted that was sold to me. I return the phone still in its package with simcards the 20 April 2019 at Mtn direct in cresta and gave it back noting was open not even the box were the phone was in ,i received a document which says that client does not want the phone ,thenon the 1june 2019 Mtn debit my account with R740 which they had no right as i did not have any cellphone nor contract with them,all i ask from them to cancel contract and give me a letter that it has been done. Since the 7 June i did not received anyfeedback. Today the 19/6/2019 i ask my wife to email again ad=nd guest what received this email saying Good Day, Thank you for your email. Please note that your email did not meet the Channel Support requirements due to no subject line or the incorrect subject line title. they do not have nothing about cancelling and unuthorised debit orders in their subject line . i am so fed up with their bad service ,i just want to get this resolve as i do not have a phone with you guys ,stop messing people around just do your job