Most unpleasant experience ever

I paid car track a month back and sent proof of payments directly to them on whatsapp. They confirmed receiving it. I do not have a debit order with them. Then I started receiving messages saying it has not been paid, I immediately contacted them and asked why I am receiving these messages, they asked me again to send proof of payment and I resent them, they said they are sorry and it will be attended to. I then started receiving messages again and I contacted them via their social media as I was not winning via the whatsapp channel and once again they asked me to send the proof of payments and I resent them again, then they said it has been sent to the accounts manager, today I received more messages saying I am being blacklisted soon and a default has been loaded against my name, I contacted them again immediately and they ask me to send the proof of payments and I respond by saying I sent them 3 times to your social media email, your whatsapp chat and directly to you Instagram. Everyone at car track confirms receiving my proof of payments so how can they add a judgment and threaten to blacklist me? I need help with this urgently as this is now going to affect my credit profile and this matter is very serious and I am not at fault, car track is. I have tried car track via social media, I have tried car track direct with email and I have tried car track on whatsapp and this matter is not getting resolved.