Auto populate based on matched data from other sheet

Registration date
Monday March 7, 2016
Last seen
May 20, 2016
Newbie here..
Was wondering if this could be achieved thru vba as have tried using formulas and vlookup thru matching criteria and it takes forever searching huge database(Have around 5000 rows)

Have 3 conditions to meet:

1. Need to match and copy column A and B from sheet (Contacts) and auto populate data in sheet (4. mobile)based on matched names in column D and E in ( based on header file

2. After above line is executed and If any data is missing in any row in sheet ( against matched name,Data will be entered or corrected manually, That info must fill in the master sheet (contact) against that matched name.

example : In Contacts sheet "deskphone" is missing for "stephen Bog"

3. Lastly if no matched name - Data entered in (4 . mobile) row manually must copy to master sheet (Contacts) end of list.

Have attached sample file