Call receive call from a certain number

Since yesterday one of my contact when it tries to call it always diverts or says I'm busy while I'm not on Call

I tried calling telkom customer service but they're not helping , I dialed all the codes they give me but nothing is working

Call only come through when it private from this contact, I checked all my call settings but nothing is wrong, all other contact numbers do get through when they're phoning me...

Calls get cut off while on the call , I'm tired of this nonsense now

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