Very dissatisfied and willing to cancel membership

So my father went to the dr in December, got the invoice and sent the invoice oneplan. The invoice was rejected since there was no stamp. My poor dad had to go to the dr to get the stamp, which he successfully got and sent back . Now its end of February and the issue is not yet resolved. He was sick 2 weeks back and had to pay out of his pocket since his claim was rejected. What nonsense is this??? Why am i paying if my dad cant even consult. To my surprise oneplan says they didnt get the invoice until he had a chat with one of your consultant 2 weeks back. Such incompetence.

He recently got a message from one of your personnel saying the invoice is still rejected provided the Dr provides the procedures done. I mean really. As per your policy a valid invoice includes: -practise number - doctor s stamp -date of consultation -name of insured that visited dr -final amount.

Why on earth do you the procedure done from my dad????

How do i cancel this membership??? I need answers