Double billed. Almost impossible to get hold of someone that can assist

I was called by Vodacom and offered a migration to a new subscription. They said that I will be billed pro-rata for the new package from date of migration, but then I got a full bill for my old contract and a full bill for the new one. It is virtually impossible to get hold of anyone to talk to with this autobot Tobi you have to deal with. They escalated the query and said they will get back to me. All I got was an sms to say my ticket was closed. Now it is impossible again to get feedback on the ticket I logged. Very very poor service!