Overcharged and no one is willing to take my call or respond to my emails

On the 15th of January, I received a debit of R3920 under my financial details on myUNISA. All it says is "Bank Journal". I have no idea what this charge is for because I haven't registered yet and all my previous fees were 100% up to date. To register, I now have to pay R6510 instead of R2590. The quote emailed to me said my total fees for the 1st Semester should be R7820 but online, it says they will be R11740 because of this unknown charge.

It's not that I mind paying extra money if there is a reason that I owe the money. I don't even mind if UNISA made a mistake. The problem is that I have tried every possible means of contacting them for 3 days. The numbers are all engaged or no one answers. I have sent multiple emails to multiple people. When I first started with them, I was really lucky and always managed to get through to someone but now I can't get through to a single person.

If anyone has a choice, don't choose UNISA. Once you are enrolled, it is mostly OK but if you have any problem at all with them, just know you will never be able to get hold of them. This is a huge problem when it comes to financial indescrepencies because now, I might lose R4000 for no reason at all and no one is willing to even take my call or respond to my emails.