Paying over R300 extra per month, not acceptable!!!

Im hoping that I can get some assistance from Telkom through this means. I have been a Telkom customer for over 15 years, I am on Fibre and my package costs me R729 monthly. I have called Telkom numerous times and asked about the same package being advertise for R399. I was told that this is only available for new customers and they cannot change my package. This is frustrating as I have spoken to one of the senior executives who advised me that Telkom can change my package to the R399 package. I am paying over R300 extra per month, because I am an existing customer? This does not make sense and make me feel like I want t cancel with Telkom. Im hoping through this complaint, I can be assisted and be put on the package that I require and not what Telkom is forcing me to be on.