Billed for two months and slow connection speeds

I have been billed for two months where the service said it is month to month, and i have only used the services for one month where my bill is over R3000. 00 where i am supposed to only be paying R1500. 00 a month, i will not recommend this service provider to anyone it is very poor and you dont even get what you pay for even after sending proof that you dont get the wifi speeds paid for that is 1000mbps and am experiencing slow speeds of between 50mbps and 100 mbps