Arnold next wrote a series of letters to Clinton, even before he might have expected a response to the 7 July letter. In a letter of 11 July, he complained that the British did not appear to trust him, and threatened to break off negotiations unless progress was made. On 12 July he wrote again, making explicit the offer to surrender West Point, although his price (in addition to indemnification for his losses) rose to £20,000, with a £1,000 down payment to be delivered with the response. These letters were delivered not by Stansbury but by Samuel Wallis, another Philadelphia businessman who spied for the British.