russian hamster turning white no more

Question
i had 2 campbells russian dwarf winter white hamsters. when i first got the 2 brothers it was about november and they were both white. pet shop man said they will go brown as it gets warmer and then white again next winter. it got warmer and they went brown, however next winter they didnt go white at all not a bit all winter. then 1 died. ive had the other now for 3 years and apart from the winter i got him hes never gone white again! i really liked him white and want him to go white this winter but he hasnt yet what can i do to make him go white and do you know why he isnt? he is kept in my bedroom inacase that has anything to do with it, its warm in there. thanks!

Answer
Dear Elle,
thank you for your question.
I'm sorry that I took so long, but I haven't been able to access the internet for the last two days.
Some hamsters just don't turn white after the first colour change and some don't turn back. There's not much you can do about this. You can keep the hamster in a cool room, but this means risking that the hamster gets a cold or another illness, so I don't recommend this.
I hope I was of some help to you
Jennifer