Hi Tony.
OK...
...there are 2 types of sticky label: permanent (price labels; fridge fronts; etc) and those "why aren't they all like this" easy off labels - similar to masking tape.
The Pullmans 'may' have the permanent type (cos we want them to stay put)
Desperate one day I Googled/YouTubed and found WD40.
I know...it's oily...can't possibly work...but it did for me! Fridge sticker residue came off like a good 'un! No anwarranted side-effects, either.
Used it ever since. Yes I would use it on a model on the basis that my models come into contact with WD40 occasionally anyway.
Try it...if/when all else fails...
Good luck!
Chris