mtn bad service

mtn keep sending me emails saying they are presenting me with a bill... when i left for Telkom since april and havent used there services sent.... i have sent numerous emails to customer care and have had no reply .... i went to long beach mall mtn... and they turned me away and said i must phone 135.. which is toll free they say.... however it is not for me as i am telkom now.....,i am sent a tax invoice ending in 1786... but cant seem to open statements. i wish them to spot sending the accounts as i do not owe they anything as i finished my contract early this year.