Supersonic's bad service

I have been billed for 30/30mbs which is R469, but my line and invoice states 15/15mbs which should be R289, i have called numerous times to which no avail, the fourth call i made the agent said that she has sent the information of the problem to the accounts department and that i will be upgrade to the 30/30mbs line and reimbursed for the past 2 months and within few days it will be resolved, it has been 3 week since then, it's going to be the third month now and still no feedback or corrections to the service or refund, very horrible supersonic service is.