Herotel rob me financially with their wifi speed

I pay Herotel R700 every month for a 6mbps wifi speed but the speed doesnt even come to 2mbps. Everytime when i complain they phone me but the speed stay the same. There will be days that i cant even use my wifi because the speed is to slow and still i must pay my full account. Not alot of people have the 6mbps speed in my area but it seems as if i got the same speed my neighbour have with his 2mbps speed