Cell c Fibre and black box

I have been with C since the beginning of the month. I have the 20G uncapped fibre. The internet has been lagging and buffering and this all for R900 pm. On top of that I received the black box as part of the deal needless to say the voucher that suppose to give you access is not working. I have escalated so many emails and each time they send me the same voucher which is not working. I am beginningbto think this is a **** to get contracts. I am so dissapointed in this service. Will definitely not recommend it. Please make sure that you vet what you pay for before taking these deals.