You can't go putting prices up because of it. :
If they ask for 8 weekly when you take it on, yes.
But not when they've been paying the same for a while.
I tried to charge more for this situation a while back, and was told "I'm not paying more, you can leave it then".
So no, that's a silly idea.
With that attitude you'll lose all your customers.
I'd rather have the £10 every other month than not at all.
I wasn't asking what to do, there's nothing you can do.
It's up to the punter.
I just asked if anyone else had this problem in winter.