Very poor product. False information from consultant

I'm on their LTE option that uses a sim card because i was told by one of their consultants that there is no fibre in my estate. But i found out that there is fibre here. Now we have a shaped internet experience which is horrible. After 100gb of use, the speed drops from 50mbps to 2mbps. On average we get 0.3 to 0.5mbps. Can't even open an email.....takes a long time to open. I think it's time to cancel. What's worse is 100gb of data finishes in 7 to 10 days because we stream through Different video apps like Netflix. I mean streaming is a norm these days. 100gb of data is too little. I guess this means I should cancel.