Sort out your admin and stop harassing me

Was asked to pay upfront in order to use the service and they send a debit order mandate with wrong date which is next month. They sent a payment link on WhatsApp which i used to pay. It's been 7 days and im still getting calls asking me to pay. I sent the proof of payment on both WhatsApp accounts email. Today, I get a text saying im late with payment for this month which is supposed to be debited only next week. The person I was talking to authorized a mandate AGAIN i don't know what for and said I will be charged R59 extra for late what what.

Please fix your admin and stop bothering me. This has caused me so much distress that I regret renewing my contract with you. I thought you were reputable. I will not advise anyone use your services never.