Did you perhaps ask them why you should update it? Always ask why so that you can also understand the problem for next time. I myself am not particularly sure whats wrong buy it doesn't seem too major though.
If they said update BIOS would fix it, then do a BIOS update as suggested. It would be nothing major but it would fix the problem you're having currently...
But please always be careful when flashing new BIOS if it need to be done manually because one single mistake and you could lost your laptop. There should be an automatic BIOS updater on Dell Support Centre so go there to download latest BIOS update...
I used to receive a message at 10% to plug in the laptop. I no longer receive this message.
it is my opinion that the bios update will not fix this problem because you use to get the 10% message before ,you could try setting the bios to defaults to see if it changes the power options setting back to normal
sorry i do not know why it doesn't warn you at 10% anymore ,but neither did dell tech support ,so i don't feel bad about not knowing .
Oh I see, thanks for telling me that caperjack. I thought the problem was solved. I have never encountered problem like this, so i am not sure how to help you. Have you try reformating your laptop although i do not like the idea.