This is common problem. The agents and underwriters are so busy that they have limited time to check the document and give credit to the policyholder/proposer. At the same time, it is duty of policyholder/proposer to check that all the info is been put in the policy like address, reg. no., CC, NCB etc.
Please write to the insurance company with the policy/cover note photocopy mentioning the mistake. Insurance company will make an amendment on the policy. And send you the amendment.Is there any way out to get that NCB Back from next year?