Slowest Wifi I've ever had for 4mb line

Hi in December 2015 I complained that my 10mb line I pay for was only delivering 4mb, so the line was changed to 4mb, but now my download connection went from 400kbps to 70kbps. Terrible paying so much for slow service and can't stream any of my internet stuff or even go onto the internet.<br> <br> Please fix the connection ASAP