My iPhone is randomly blocking contacts

Smart Phones neither have the intelligence nor the hostility. Hence we need to look at our device settings and the way we synchronise our smartphones with Mac/PC/iCloud and also how careful are we in sharing our sensitive and valuable pieces of information with friends and family members.

Be careful when sharing the device's sensitive and valuable information with friends and family members.

Thumb Rules:

1. Don't hand over an iPhone to kids or to a stranger without Enabling Guided Access
2. Don't share Apple IDs
3. Don't Jailbreak
4. Don't share sensitive information pertaining to your device
5. Don't give in to Phishing
6. Don't plug in your device in Airports and Public places through third-party cables and trust the device. Beware of Juice Jacking. (Especially in India)
7. Don't leave your iPhone unlocked and unattended in public places like offices, schools, malls, etc.

My I-Phone keeps blocking my contact numbers when I did not request it. When I unblock each one, they then show up in my blocked numbers in my settings. When I delete those from my settings, my contacts are blocked again. How can I fix this?