Upgrade 1 to 10 devices

I have 1 device Internet Security (enddate 24 October) and I device Tune-Up (enddate (18 December).
How can I upgrade to 10 devices Ultimate ?

Hi Luc, 

I request you click on the link below to reach our AVG billing team via live chat or call support to help you in this.
https://support.avg.com/support_sales?l=en
Thanks in advance.