Change Shipping Costs on Subscription Product

Site URL: http://www.lostmap.com/club

Hi there ... first time poster, please go easy on me if this question has been asked a million times. I couldn't find an answer to it, when i did a search.

I'm wondering if it is possible to change the shipping costs on a subscription product, and for it to be implemented on existing subscribers? Postage in the UK has just gone up, and so I adjusted the shipping costs on my subscription product by £0.10.  I currently have 245 subscribers to this product, and only brand new subscribers are having to pay the new adjusted shipping cost (which is £0.70).  All existing subscribers are paying £0.60.

I asked Squarespace about this via email, and their advice was to have my existing customers cancel their subscription, and then resubscribe ... but I desperately don't want to do this, as i'm positive i'll lose a significant bunch of customers. It seems unfair, to me.

Is anyone else experiencing this problem? Is change possible?