Hi Bree,
I really feel for you.... But here are a few suggestions..... rayon is made from treated natural fibres so it doesn't melt quite so easily.....so are you sure that he didn't use polyester? That said, ironing on the reverse on a towel as recommended by our posters in definately the best way.... Secondly, you need the fabric that you send to be larger than the frame the embroiderer needs to put it in. As Nessie said.... Embroidery should not be wrinkled.... Good stabilising and a tight frame should ensure that wrinkles do not occur......
Finally, I wished I lived closer as I would do the embroidery for you......!!!!
hugs
Caroline