car insurance for my 16 year old

Hi there

My son has been given the enhanced rate of the mobility component of PIP and wants to learn to drive. He has had his license updated so he can now learn but I can't find anyone who will insure him at 16. Every insurance provider says it is illegal to drive until you are 16. the 2 companies that I have found have quoted me over £3000 and want it all up front. Does anyone know of any insurance companies that can help.