Telkom mobile service on contract extemely

I entered into a contract with Telkom last Month (April) telephonically, they promised to offer a Wi-Fi with 10GB at R169 and that was fine, they deducted the amount on the 11 april 2019, the order was process and approved on the 15th of April and they promised to deliver within 3 - 5 working days, they came to deliver the device at work on the 18th of April 2019 around 3 pm and i was already left since it was the easter holiday then the courier company went back with it, so i had to fetch it myself at the courier campany in Durban, when i got home, the device was not working, the next morning i went to telkom gateway to ask them about the connectivity, they said they can't help me since i ordered it online, so i should wait for 2 - 3 days for them(call centre) to RICA the sim card. I had to call the call centre in order for them to RICA it then is started to work but it was extremely slow when trying to connect, after that it showed that it has no data untill i deciced to got to pavilion to check on last week Thursday (02/05/2019) and i told them that i am not happy with their service, and the device and the guy (saaid to be a technician) told me that there was only 2GB and it was finished so i therefore requested them to cancel it, then the technician told me to come back the next day(friday) since i didnt brougt my ID in order to do the cancellation. I went there the next day then the lady took my ID mentioned that she has initiated to cancelllation process however i should wait for 30 days in order for them to cancel it and she emphasized that i shouldn't use it so that they wouldnt be additional charges. Today (07/05/2019) i received an email with an invoice of R 204 that will be deducted on the 15th May but i still haven't used the decice, when i call them the lady told me that they pro-rata the data that is why they gave me 2GB and when i ask her why don't they pro-rata the charge as well, she cant give me a clear explanation and when i ask why are they charging me another R204 for something that i havent used she said i am suppose to use it and they havent received any cancellation on the system therefore the contract is still on and they will charge R 800 pls the amount of the device should it happend that i want to cancel since the cooling-off period is over. i told them that i have been complaining about the device connectivity since it started to function and chances are the coverage is poor where i stay and the person who initiated the contract coud not verify my address for coverage.