I did repair an old quilt that was just squares for a lady. Many of the pieces were frayed at the edge and I ended up taking the quilt apart, substituting squares that were too badly damaged. Sewing the top back together and retied the whole thing. It was the last momento she had of her dead mother so I couldn't say no. She offered to pay me but I told her to make a donation to my favourite charity. She did and sent me the receipt for $50.
Since I couldn't put a price on the amount of work involved, it worked out well but never again!