Thank you for reaching out to us and welcome to the community.
I am sorry to hear that you having issues linking Alexa to your SB 700 however I would like to help.
If you have already set up the Amazon Alexa voice assistant in your Bose account via the Bose app but Alexa responds that the Bose Skill needs to be added when you make a voice request, I would recommend you try the following:
Remove and re-add Alexa in the Bose Music app.
In the Alexa app, disable and re-enable the Bose SKill.
If the issue still persists restore the system by following the instructions below to its factory defaults and perform the setup process again.
Open the Amazon Alexa app and view the smart devices associated with your Amazon account.
Remove any instances of the Bose product you want to reset from the smart devices listed in the Alexa app.
If you do not plan to use other Bose speakers with your Amazon account, view the installed Skills in the Alexa app and remove the Bose skill.
Open the Bose Music app and remove Alexa from your Bose account. For more info, see Adding or removing the Amazon Alexa voice assistant.
Remove the product from your Bose account. For more info, see Removing a system from your Bose Music account.
On the remote, press and hold the Power and Skip forward buttons simultaneously for 5 seconds. The soundbar reboots and, when complete, the light bar glows solid amber.