Clevis
Just a guess, by the way.
The exteriors would have to be repainted. Can't quite remember the liveries they carried, but either BA or Maersk. Niether would like duo to continue operating in their colours now not involved. Corperate risk I supose.
As for the interiors, with the exception of colour choice, duo was selling a product.
Whilst not quite Silverjet, however there is one link, it would be like booking Silverjet and getting on a white tail, not refitted until it turns the corner. No product.
By your maths, 40K to spray livery and then white tail, times 5, 200k. Cheap advert......... Had it carried web and phone contacts clearly.
For all the bad points mentioned here, a lot of effort went into the duo brand, at grass routes. The advertizing was a different storey.