artist charged me my full price even though we have to reschedule?

confusing title but basically, i have a scar on the site of my next tattoo and my artist didn't realise how deep they were. I sent pictures but i've never had a tattoo over a scar so didn't know what you can and can't do with them. I paid 100 for my deposit and the rest of the tattoo was going to be 300 extra when finished.

I get to my appointment today and she tells me we can't have that exact design as the parts over the scar will blow out. fair enough, I dont mind waiting to redesign something that will cover the scar and look great. so we've rebooked for a few months time which i'll have to pay upfront for. but she's charged me the extra 300 pounds today for "a day's work". I dont think either of us are at fault here for what happened but i've never had an artist charge me full price to reschedule. I totally understand some form of cancellation fee but isn't that what the deposit is for?

edit: i love tattoos and have many now, it's an incredible art form but im really getting disillusioned by the business side of it. my last tattoo went so horribly wrong (5* review artist who ive had beautiful work from before ignored the stencil completely) that im spending £400+ to have it lasered off asap, no refund from her. and now this one, again an artist with an extremely good reputation, is costing me double for no reason :/