Incorrect ADSL billing from Telkom

Recently moved premises and down graded from a 10mb line to 4mb line as there was no 10mb available in that area, now I’m getting billed for both lines with a total of R1814 and I only have a 4mb line and no one at Telkom seems to know what the hell is going on if it is clearly showing on my invoice that I’m billed for 10mb line (WITCH I HAD AT MY OLD PREMISES)and a 4mb line what I have at my new premises now. PLEASE TELL ME TELKOM WHAT DO I HAVE TO DO TO MAKE YOU UNDERSTAND SOMETHING SO SIMPLE AND FIX IT????????????????