Terrible FNB experience. Payment failure/hold

Hi. I did a FNB to FNB banking app transfer on Saturday 13:10. No proof of payment was received by the recipients. I went online the payment shows successful. But when i try verifying the pop it gives me a E-766 error. On my banking app it show the payment is pending. Its now 18:32 and the payment hasnt yet gone through. I called into the help line twice both times the call got cut, i then did a second payment to the exact same account and that worked perfectly. Why did the first payment not go through and when will it. Terrible experience recently. My bank card expired and when i went into the branch to make a new one, i got told i need an appointment first. Please fix the payment. Thanks.