Proof of payment made

For the last month I have been trying to get a simple proof of payment from Momentum as the supplier (Dr) is unable to find the payment made to him. Despite numerous request for the proof (date, back acc used and amount that was paid) I still do not have this and now they are wanting permission forms filled in as my company recently changed our email address (just the format, my name, surname and company name is still in the email address) I am thoroughly frustrated with Momentum and I actually fear for when I should need for a medical emergency if asking for proof of payment made is such a big fight and effort <div><br></div><div><em>(Supplier name changed from Momentum to Momentum Health by Hellopeter.com)</em></div>