If she has visibility of your FB (as you seem to have of hers), give her a couple of hours to do transfer then if no response, put a comment on FB saying that you have a spare ticket due to non payment, is anyone interested. It may just make her realise that you are serious!
Sometimes you do need to be upfront or people take the mickey.
I meet with 2 uni friends most Decembers, overnight, for a pre-xmas get together. Another uni acquaintance joined us last year, at my suggestion as she lives near me.
I booked this years hotel in Sept, amid a flurry of texts to all others to check it was ok. I had to pay full amount in advance so asked for payment within a month, before my CC bill was due. Newer friend asked if she could wait until pay day (despite her and her DH having v well paid senior jobs & not short of money from what I understand!)
No probs, but when I didn't get anything on her pay day, I messaged her again a couple of days later. Money appeared straight away. I have also asked if she can drive this year (given that I drove last year, as it was first time she joined us). She did give me petrol money, but as my DH said, why should I drive every time.
I was never the type to let people walk all over me, but I am even less so as I get older (now in fifties). I certainly wouldn't have let this go on from Feb until the day before the concert.