TOTALLY IRRITATED WITH MTN's NON EXISTANT SERVICE!

I have been trying to contact the call centre (808) for three days in order to request them to cancel my voicemail on my phone as I will be travelling. I have been cut off EACH AND EVERY TIME before I get to speak to an operator. In absolute frustration I then got my mom to meet me at and MTN service provider (she is also travelling) so that we could sort this out in person, only to be told they cannot assist only the call centre can. I explained to her that the call centre basically does not exist as no one ever answers before you get cut off so could she not perhaps assist but No. She instead advises me to cancel all calls from my phone and should I need to make a call well bad luck its not going to work. Seriously - is this what MTN calls service delivery?????? I have been with MTN for many many years but am starting to look to other service providers as I'm sure their service levels will beat this!!!