Over chargeing and refusing to pay back.

I went over to the Vox telecommunications solution in July 2017 since to try out their services in preparation for Fiber availability im my area. One of the services i was interested in is the VOBI VOIP they offer as part of the fibre package. But before committing to the more expensive fiber package witch includes the VOBI i thought it best to try it out first. So i signed up for the R25pm + calls VOBI. The sales rep who helped me promised me they can use that number for the unlimited VOBI once my fiber is installed. In October the Fiber lines were finally finished in my area and they installed my fiber and Thiani helped me with applying for my Fiber package. I told him to cancel the ADSL and move the VOBI number over. This was not done. When i got my first invoice i phoned to complain about it so they canceled and refunded the adsl. However they told me they will get back to me with regards to the VOBI. Then the game of cat and mouse started. I kept phoning in every month to complain about my bill. They tell me i need to speak to THIANI. They put me though and either the phone just drops or he not there and i get told he will phone me back. Months goes by with no results till finally last week I manage to get hold of him. He told me he will fix the issue. So i also requested that i get refunded the double payment for the VOBI since October. And he told me no. WHAT? How does that work? I told him its unacceptable they messed up and now i have to pay for it? So he told me he will phone me back later that day. That was last week and guess what? No call back yet.