She asked for a signer to be provided and was refused, but was offered free tickets for her to supply her own signer. Not happy with this she forced the issue through legal channels, the promoter relented and provided a signer - but because the signer was only provided for the headline act and not the support acts, she's suing.
I think she is being unreasonable.
Her contention that missing the support acts is akin to only seeing the final 20 minutes of a film is complete bullhsite and you cannot compare the two. Her prime (probably sole) reason for buying the tickets was to see Little Mix. I doubt the support even entered her mind.
She's trying to make a point.