Worst internet ever

This company is charging me almost a R1000 for a 50mbps-50mbps per month, but my speed is never this speed.... I am not happy at all and want to cancel my contract because they are not sticking to the contract. What to do???? I am very disappointed in their service, they try to sort out the problem but they are not fixing anything, I just feel it is unfair because I have to pay for this line,,,, and not getting what I pay for - worst fibre company ever Accelerit Fibre