I'm a magazine editor and normally work full time but do some freelancing on the side. Recently took on a small charity magazine, negotiated a price for it that was a lot lower than my usual fee, but felt it was a good cause and wouldn't be putting me out of pocket if I could do it in two weeks. Anyway, as it's panned out, that was wildly optimistic, and it's taken weeks of my time (and my designer's), with endless changes to copy and layout being required. I edit a monthly magazine as my day job which is more than twice as long and never have this level of stress! There's been a lot more micromanaging than I'm used to. I would not have agreed to the fee had I known this, but I don't want to blow them out, having got this far down the road. I've never had to renegotiate a contract, so what would be a tactful way of doing/phrasing this? Any suggestions welcome.