Whatsapp surely doesn't contact anyones contacts to collect bills or harass people in other ways. The contacts have not agreed to be spammed for these purposes. Therefore it is understandable Google doesn't want you in their store, since these contacts are quite likely to be other google Android users and Google has an interest in protecting their user experience. I would suggest you remove this 'feature' and use a debt collecting agency instead. The reason they give is i think irrelevant. They keep using the same reason which means they don't want to spend anymore time on you. Maybe you could pay for a google consultant to have your app become compliant again.