Dumb phone

I have got a Nokia 105 dumb phone for my son. Despite putting credit on it via the Lebara website , when I try to make a call it says there is no credit .Trying to set this thing up is 10 times more complicated than my iPhone. Does anyone have any step by step idiots guide plead

AngelaP9 has the payment for the attempted top up actually been taken or has it just failed to go through?