Bad cutomer service

I had a contract with MTN,since I knew that it will expire on the 27th of March 2015 I did call them in early February,the guy who helped me said I must call the same day my contract expires.I did call them on the 27th of March but I had to hold a phone for more than 20 minutes and nobody picked up so I sent them a cancellation email.today, after 45 days from the day I sent them an email I received a phone call from them to tell me that they cancelled my contract but they will still deduct a last payment .should MTN deduct money from me I will never take out a contract from them and I will make sure that no-one close tome takes a contract with MTN ever. I did call 30 days before my contract expires but their employee told me to call the day my contract expires so that can't be my fault.