How can we get our ‘refundable’ deposit back from Hire Booking Centre?

We returned our campervan undamaged but we are still owed £1,250In October we hired a campervan from Hire Booking Centre, which operates out of the same address as Motorholme which you have written about before. We had to pay a £1,250 refundable deposit. We returned the vehicle but, despite repeated requests, are still waiting for our deposit. The van was signed off as being undamaged so there are no problems on that front. On my most recent call I was told the issue was with the fin