Greetings;
I have experience with this kind of work, and I can tell you right now that you can't expect 100 % completion of the work. I would say about 70 % at to most on average. Off course if the websites are big companies it would be logical that they have that information’s available publicly and that those information’s are correct. So it really depends on kind of the websites and those companies / people whose contacts we are looking for. Phone numbers are extremely difficult to find in average...etc.
IF you are interested we can discuss more , prior the job hiring.
I offer my 100 % cooperation , and would complete the job asap ( 1 day , 2 days at most, depending of the difficulty of extraction of those info’s).
Regards;
Bacc. oec. Ante Klisović