If you have already done this only then bid. NO time for trial & error.
Require Whatsapp messaging application installed on my server which can:
1) Do mass messaging, without being blocked by Whatsapp
2) Can first filter from a list of numbers imported to send only on numbers that are active on whatsapp
3) Can help track replies that come & sort & filter the lists based on responses or lack of the same.
4) A simple UI also is acceptable. Cannot operate this from just the command prompt.