I'm sure I've heard a few people mention EKM Powershop so hopefully someone will be able to give you more help tomorrow.
Discounting the readings is a good idea as it solves the problem short term and anyone who shops with out looking at the P&P will think they're getting a bargain
With a bit of luck the EKM Powershop support will be able to help you, I've pestered the living daylights out of the Roman Cart people and they are always very quick to reply ... 9 times out of 10 they can solve the problem so fingers crossed.
It's a lot more straight forward for me as I sell big bulky packs of baby bedding and gifts that need protecting in the post so the majority of my stuff goes by courier. the smaller stuff is a challenge though isn't it. I find it complicates matters when something small is added to something else small that then requires more packaging than the weight allows for ... bit of jiggery pokery with the weights and I'm still getting caught out every now and then.
Sleep on it and if the support team don't get back to you hopefully one of the gang will help you in the morning.