It won't show up on-line in My Virginmedia until your next bill is generated. The system does nt work in real time (we wish it did). Internally VM need around 24 hours to process, judging from other answers to questions like this. Your evidence of payment is your bank statement or card statement showing you made the payment.
Superuser 2017/18 Use Kudos to say thanks Mark answer as "helpful" only when the problem is solved Please don't send me private messages unless I ask you to. I do not work for VM. The advice I give is based on my best understanding of VM policy and practice. You rely on it at your own risk.