Outrage !!!!!!!!!!!!!!!!!!!!!

I got a call on the 17th of April 2018 for a upgrade on my internet package. After a lengthy discussion and what seemed to be a fair deal I agreed to the proposed option. This was from my current 10mbs uncapped to a 20mbs uncapped package. I was told this would be just a R260 +/- and I would get a modem and media box and all sorts and this would only happen when installation happened as my current router could not "do the needed speed". To my surprise I got a very large bill from Telkom showing this was active from the 24th of April and that it was not a R270+/- increase but a R680+/- increase. This I find unacceptable. Firstly I have not received anything yet (modem, LIT box, installation) and can not use this speed because of my current modem as it cant go higher than 12mbs. Then secondly I was told explicitly on the impact on my bill. I can not afford this nor will I PAY as this was not what was told to me or agreed on. So how can I pay for what I can not use. Please go back on the call date 17 April 2018 at approximately between 3 - 5 pm.