Review ASAP, I want answers...!

I app**** for the Mitchells Fibre, through cool ideas on Sunday 09/02/2020 and made immediate payment on their website. the next day I received a call advising I need to email my proof of payment which I have done immediately yet they are still telling me they have received no payment and that i need to wait for them to investigate...the payment shows clearly so what is the issue...I am so damn disgusted by this pathetic service and have lost my complete trust in this service provider...