More than double charged and no customer service to assist query

I got a new service for Webafrica 20MB fibre line for R799 a month. They connected me on 6th October 2020. I chose the 1st of every month as my debit date. Anyway the 1st was a Sunday and on Monday I was debited R1692. Bearing in mind that it's actually eve less than a full month yet I was more than double billed. I went to their whatsapp chat group with no assistance. Literally waited for hours with a chat bot giving allowing for selections but no customer service agent got back to me. I called their customer support and help on for more than an hour with nobody picking up the phone. On their website they mention that they charge pro-rate this means that I should not have even been R799 because the days is less than a full month yet I was charged for more than 2 months work of service. I find this very shady and unprofessional.