WebAfrica's line downgrade options does not work

During October I requested that my Openserve Fibre 40/20Mbps Line and data to be downgraded to a 20/10 fibre at the end of the month. In the beginning of November I logged a call to find out what the status was as I received messages stating that "You have hit your FUP threshold on your uncapped internet package. " My call was ignored but I assumed that this was due to a bug with me downgrading the line. At the end of November I received an invoice from WebAfrica which indicates that the line was not downgraded. This is now costing me allot of money which I have not budgeted for. There is no way for me to proof that I did in fact request for this line to be downgraded. WebAfrica cleverly do not send any confirmation emails or any correspondence when you request to downgrade a service. They send messages when you activate a new service though. I was well aware that I needed to downgrade both line and data services and I believe I did request correctly.