After your first top up you will be asked to enter a 4 digit code into MuchBetter to verify that you are the owner of the card used to top up.
You can find the 4 digit code on the bank statement of your card, it will appear after MB, MBETTER or MUCHBETTER*
Sometimes it can take 24 hours to appear, if you do not want to wait, or if you do not see it in your statement, call your bank and ask them to read the descriptor of the transaction for you.
The 4 digit code is 4187 in this case.
Some banks may not show the code, in that case, please email firstname.lastname@example.org with a screenshot of your bank statement and a photo of you holding your card, covering the middle 8 digits.