National Savings and Investments Childrens Bonus Bond

I have given up trying to open a National Savings and Investments Childrens Bonus Bond account. The post office took my minimum 20 pounds for each of the 3 children's accounts and rejected my offer of my passport as proof of ID saying it wasn't needed. 2 weeks later I received the applications back saying that children over 7 had to sign the application themselves, and also submit their original birth certificates by post, or verified copies. This has all become too much of a hassle and I have requested my 60 pounds be refunded and I will go to a local building society where I can show all the documents required qithout having to send them away.