Very poor customer service

I took out a new cellphone contract with Vodacom. I followed the online route as it was more convenient. There was no option for me to choose my cellphone number. When I wanted to do a Port-In for my current cellphone number, they said that I could not change my number and I have to fulfil my contract with a new number. I have been using my current cellphone number for years and I do not want to change it. I phone customer care on Monday and I have yet to receive a response from them. I do not know why it is so difficult just to change a number on a contract? No help, no customer care, nothing.