Veterans UK grant for mobility cars

Hi my friend is in receipt of a war pension which entitles him to have a mobility car. Due to his disability he has been awarded a grant to cover the costs of requiring an automatic gearbox. He was relieved as doesn't have funds for the advance payment and even had to borrow money for the deposit when ordering. He has been told today that the grant is only payable 2 weeks after collecting the mobility car and that he needs to find £500 himself to pay up front. Surely the grant is payable to avoid this sort of financial hardship? Any advice would be greatly appreciated.

So far just veterans UK who referred him back to motability, although they did think it was ridiculous too. I will try the legion next on his behalf. Thanks for replying so promptly.

Royal British Legion also referred him back to motability, it was worth a try though. Thanks.