How long have you had the number?
If it's 12 months then simply order a new dataplan (which will come with a new number) and cancel the old one when the new one is active.
If it's less than 12 months then it may be difficult. (You can always buy an additional plan of course and then wait for the 12 months to expire)
I am just another Sky customer and my views are my own even if you don't like the answers
