renogatiation of present arrangement

I have asked for a new rate for my internet since I found 100Mbps was way too much being a senior I only look at movies on  Netflix which after inquiring I only need 5Mbps.  To my surprise, they sent me another ' contract' to which I have not adhered to yet since I only requested a quote, and not at all what I wanted.  How can I  cancel this new 'contract' which is not at all what I asked for....and can you believe I am already being charged for exceeding my transfer capacity which they have set at 150 GB this is totally not what I asked for.....incredible.