If you sent them your MAC code then they are sorting it. You won't be without internet.
When I switched from Tiscali last year (wish I ruddy hadn't now) I had to ask for my MAC code. After them dancing around the houses and giving me their sales rebuttals (
) they finally handed it over. Then I passed it to O2 who started the process, but you will pay up until the date your next ISP give the OK.