Why is she texting you anyway. Shouldn't it be official by phone or is it just me.
Just seems a bit unprofessional and 'lazy' and thats prob why she thinks she can take the piss. I have a very good relationship with my drivers and we have a good laugh as long as the job is done but as soon as they f**k about they know I'll have them. As mentioned above it just shows her lack of respect.
Good luck fella