Paid for services that I can’t utilise

I’m really not happy with Vumatel fibre and it’s ISP, SADV… On Monday, the first of July I made a payment using their Payfast option online, Vuma has not yet allocated the payment, I can’t utilise the services that I’ve paid and I can’t even get hold of these service providers. SADV has a WhatsApp but they respond after 20 hours but it’s written that it’s a 24 hours service. I even sent them an email with all the proof of payment and payment confirmation from Payfast but my fibre is still suspended. Can Vuma change my ISP because SADV is not reachable and you can’t even call Vuma.