If it’s the vynal type, any automotive shop can do it…. You can supply approved material or test samples of what they have to meet flammable material requirements….essentially self extinguishing test you can cheaply do by following a AC and having your A&P sign it off. Most automotive materials meet SAE flammable requirements which also meets most or all FAA requirements. So, ask for fabric SAE data and conformity sheet, look up exact cited SAE test and compare with aircraft requirements which will likely meet. Save you about 50%