Dress stain after dress fitting

I had my first dress fitting 4 weeks ago. During the appointment, I got a sharp injury from the pins on the dress . and have a small drop of blood on the dress right in the tummy area . The staff reassured me and said they will sort this out no problem.
During my last dress fitting, they said my dress was a sample dress and did not say anything about the stain and asked if I want my dress for dry cleaning. I did not remember the incidence regarding the blood. My bridesmaid then realized there’s a large stain (brown water stain) at the front of the dress. It is definitely shown under light, and can be seen. They said they will try cleaning it with water again. And if that is not sorted, I have to pay 95 pounds for dry cleaning.

Is this my fault to get blood on the dress? Or is this responsibility from the fitting shop. I am already paying 360 pounds for the dress fitting .