Mweb Unable to remove our Domain from their exchan

So after being a mweb customer since 2011 we have decided to change our email provider due to constant email outages and expensive billing R79 for a 2gb mailbox per user. Now we are facing the issue that any mweb customer who attempts to email us gets a bounced message stating that our email does not exist. We have phone mweb many times to ask them to remove the domain from their server but no one there knows what i am talking about, they are *********** and untrained, they have no clue as to what is going on, their support staff is not supportive but leads to more frustration that what you had when you first called them. THis is a warning to all, STAY AWAY FROM MWEB, you will lose customers and valuable business time.