Incorrect charges!

I am so fedup with this country and the lack of service from suppliers it isn't funny anymore. In April I did an early upgrade on my contract with Vodacom. I was advised by the consultant I won't be double charged and that my new package will be charged in June as Vodacom charges the following month for the previos months calls. In May I was charged double the amount! I called the call centre they advised that this was their mistake and I must only settle R1998. I did that and informed accounts. Now my phone is locked as I owe money to them. On Saturday the call centre they are investigating the matter. Today I was advised no one is looking in to this and I must pay up the money!! For once I wish people can do their job right and not inform the client incorrectly!! This is so appauling and I am totally disgusted! when my contract is up I am moving service providers!!!