Please help

My name is Julia makgana Seleka I recently upgraded with MTN through the Retention department in June 2020 .Where took a package that has laptop that comes with the router and data.i am supposed to receive 12 gigs of data in total,8gigs for night time and 4gigs for anytime. But to my disappointment I only receive 2gigs of data every month I call MTN to rectify this error but even today as I write this email nothing has been done to resolve this problem I have countless references given by consultants promising that the matter will be solved and now I am paying for a package that I did not sign up for. Please help cause if I don't pay my credit status will be affected.