Cancellation challenge

I ordered a route with Mweb on the advert it was written R619pm, to my schock i am paying R898, the network of this wifi is pathetic i have kids doing home schooling and this frustrates me.Iv been trying to communicate with their live chat which is useless i never got to be helped in this live chat, when you call the call centre you hold 68 minutes and they will end up saying no agent available. i want to cancel this and it is so difficult you cant do so as easy as when you order. can i get help to cancel this wifi please