You shouldn't have to moderate your conversation topics because someone struggles with the subject; perhaps if she had stayed she would have learned something, and I am sure you would all be willing to help.
I don't think there are courses on using mobile phones, are there? Computers ,yes, but it does help if there is someone nearby to come to your aid when you are stuck. I can manage my computer fairly well, but mobile phones confound me and I rely on my adult children and friends for help.
My son, who works in IT, says you can try and try with a computer but unless you are guided through the initial stages you can so easily go wrong. Many IT instructors explain once and are astonished that you aren't familiar with the terminology, (icons, cursor, cut and paste, drop down boxes etc etc) and cannot remember the sequence of instructions immediately.