Terrific, happy seamstress lady near Mueang Pizza Resort and Buriram Expats office.
Recently had a pair of jeans shortened. Beaut job. 1hr. 30 baht
Have also had shirts altered to fit me properly. Very reasonable price.
She can do all sorts of alterations, not only with clothes, but any manchester products.
She's in a quiet obscure soi which is a little tricky to explain the precise directions, so PM me if interested, and I'll make sure you find her.
She speaks no English, so perhaps bring your lady to translate.