Online Payments is not working

I am very upset at the way cellC are handling my account and the threatening tone of their email from *** which does not accept repllies.

On 24th December 2024 I went online to try and pay my account of R298.97 which was due on 31/12/2024. their website said that R100.97 was due. When I tried to pay R298.97 I received this message: :"Sorry, your payment can't exceed your amount due." so I only paid R100.97"

Now their website says the amount due is R0 and is due on *** and will not allow me to pay anything even though I owe them money