Bad Service

From the first day i enquired about uncapped internet from Telkom i app**** for a 4mb Uncapped ADSL line. One month went fine had to phone about a problem with my internet the lady helped well and i asked her about the speed of my line. She said im on a 2mb line. I said that i apl**** for a 4mb line and she helped me to go to a 4mb data line....now for the last 2 months ive been throttled at 200 GB what meant that im actually on a 2mb line. I have been paying the last 6 months the amount of R657.00 a month. The problem with this is that when i phoned because of the throttling the woman told me im on a 2mb line. So my problem is...im paying for a 4mb line and only been using a 2mb line. Again im paying for a service that im not receiving. I need to be reimbursed for those months that ive been on a 2mb line and paid for a 4mb line. Also i want to stay on the 4mb uncapped without worrying about being put on a 2mb line. I need this solved and quickly as possible because if i can pay on time everymonth i expect this company to give the service that they promise to loyal customers.