Waiting more than 9 weeks for delivery of children certificate of Registration

[Learner101]

Please I need help with understanding what's going on.

I got a letter from the H.O. dated 20th November 2019 stating that my children 's request for registration as British citizen was successfully. They have returned my supporting documents to the address of my cousin in the UK.

I gave my Nigerian address in their applications as that's where we currently reside. They insisted on sending the certificate of registration to our address in Nigeria.

They stated in the letter that if we failed to get the certificate after 12 weeks we should inform them via email.

Am I suppose to believe that it takes more than 9weeks for mail to get from U.K. to Nigeria?

Why didn't they send the cert. with registered mail we would have gladly paid for it.

Apart from waiting for the 12 weeks to end using the date on their letter. What else can we do?

Please any insight or suggestions will be highly appreciated.