If bailiffs have taken control of my vehicle, can I force them to sell it?

No

There is no procedure in the enforcement regulations that enables a debtor to force the sale of controlled goods.

When a bailiff is ready to sell controlled goods, he must give the debtor a Notice of Sale,^[1] not less than 7 clear days from removing controlled goods to sale.^[2]

^{[1] Paragraph 40 of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[2] Regulation 37 of the Taking Control of Goods Regulations 2013}