I would call and complain, you are paying for 1 hour and she was only there for 40 minutes. You talked to her about her doing NILIF and bite inhibition, if she agreed to do it and she isn't then I would want a new dog walker.
Who knows how many times she cuts out of there early.
Sinister ~ 5 yr old black male GSD 3.11.09
Draco ~ 9 mth old male Dalmatian 6.30.13