I doubt that such a number even exists. The guys who drive for Yodel are all self-employed, so the only phone numbers they've got are for their own mobile phones. It's likely that a driver serving Burton-upon-Trent will be working out of the Stoke-on-Trent depot (01782 836071 or 01782 599889) or the one in Loughborough (01509 219079 or 01509 239421) or Lichfield (01543 556000).
However I doubt that you'll get any further by calling those numbers than you will by phoning 0844 453 7443.