DH has vehicles on HP for work. He contacted HP company, who confirmed that the settlement figure for one vehicle was £11k and the second vehicle was £16k, so total £28k. This is one HP loan, for 2 vehicles. He has sold both vehicles for these amounts just to get rid of them and clear the HP.
He paid the £11k settlement figure for the first vehicle and he was about to pay the £16k for the second one, when the HP company said that they made a mistake and the total due was really £36k so want another £8k.
As they confirmed the settlement figures in writing, can they now ask for the extra cash? It wouldn't such an issue if he hadn't already sold them for the figures given. Whether he sold them for the right value is another issue, here I am just looking for the legalities regarding the written settlement figures.
Thanks for any guidance.