Horrible management and assistance with account.

I asked for my fixed lte package to be changed to a cheaper option in December before the 20th. As the self help system was not available at the time i contacted the relevant department and was only assisted weeks later in the matter. When I was informed that they will change it manually i asked for it to be cancelled because I was moving to my old residence and had to have the full package again. I was told the request would be cancelled. Yesterday I noticed that my internet was off and with further inspection i noticed that my package was never changed back and i only got the cheaper data package for this month. I had to purchase top up data due to this negligence. All of the above arrangements were made before the 20th of December and January thus I do not understand why I was assisted so poorly in this matter. What can be done to correct this? I have contacted the relevant departments numerous times in the past and have everything on email but I have received no clarification with regards to this matter.