Huge Upholstery Disappointment

Did you provide the foam? Did your quote for the job include foam?

You insisted on certain materials, which means the shop was already doing something different from what they would normally do. Could be a case of them doing exactly what you told them to do, or at least, what they thought you told them to do. $125 to fully re-upholster a seat is pretty much nothing, especially if they were to provide all the materials. Sounds to me like you paid for a cover, not a full rebuild.