No service

My 2 year ADSL contract ended on 26 May 2015. I called and asked for an upgrade from 2M to 4M on the same day. The call centre lady said it will take 1-2 days to upgrade. But they never did that, I was told no ref number was found on their system when I called again 3 days later...and the guy named Khayalih told me the lady put 2M instead of 4M...that's why it did't get the upgrade. I was given the ref no. ***A. After another 3 days I called again, same thing happened - no ref no. was found on their system. I was given another ref no. ***A...and then same thing, I called after a few days they said this ref no. was in the system: ***A. Everytime the call centre guys tells me a different story. Some say 1-2 days, some say 3-7days, and I just call them again just now..the lady said it will take 14-21 days! Hahaha what a joke! And my line is still on 2M but I was charged for 4M - invoice number 506A***d. I don't even know what I should do now because there is endless waiting and no one is trying to help, call centre guys pushes me to technical dept, vice versa....is there anyone who understands can help?? Can I speak to a supervisor or someone who knows the thing!