Renewal Of Child'S British Passport

I am having to renew my child's UK passport, she was 3 weeks old when the picture was taken and is now 4 years old, and this is causing problems with immigration both in Thailand and Malaysia. Does anyone have any experience of a child renewal since the processing moved to Hong Kong? The websites are contradictory with one page requesting that the old passport is sent with the application and one page saying it is not required. I cannot locate an actual price for renewal with again one page listing a completely different price than another! Before anyone kindly suggests I ring the helpline, I have done that but no longer have a credit card so cannot pay the 65 pence plus VAT per minute that they require before answering any queries!! Many thanks in advance.