I'm so sorry about this - the problem seemed a bit random at first so we had to give free postage to those that were getting ridiculous shipping costs. I am really not sure what the problem is although I will check the rainbow weights obviously!
I am now in the process of setting the postage to a flat rate of £1.50 so feel free to order without any risk of having shipping charges! I thought it had gone a bit quiet on the shop
I am already going through the orders we have received and will be refunding any dodge postage costs.