She initially thought the email was fake, but after realising it was from Ticketmaster she said she does not intend to buy tickets from the company in the future, despite being a loyal customer.

Loyal customer pretty much means the same as regular concert goer.

I go to quite a few concerts and all of my tickets are bought from Ticketmaster in some form. I wouldn’t call myself loyal to them as I’m forced to choose between Ticketmaster or no concert.