Python - ayuda no saca el subtotal y el igv osea no lo suma

if __name__ == '__main__':

# calcular el impuesto
mnto = 100.0
igv = 0.18
totalfac = 0.0
imp = 0.0
op = ""
des = ""
alm = ""
cn = ""



while True:

print("| RESTAURANTE CHILLCCE S.A |")
print("| MENU |")
print("|===============================|")
print("| A |Desayuno |")
print("| B |Almuerzo |")
print("| C |Cena |")
print("| D |========== SALIR ==========|")

while True:
op: str = input().lower()

if op not in ("a", "b", "c", "d"):
print("Opción inválida, ingrese nuevamente")

if op == "d":

print("| BOLETA DE VENTAS |")
print("|===============================|")
print(f"| Subtotal : S/{mnto:.2f} |")
print(f"| Igv : S/{imp:.2f} |")
print(f"| Total a pagar: S/{totalfac:.2f} |")
print("| |")
print("| Gracias por tu compra |")
print("|===============================|")

else:
print(" Elija su Comida\n")
break

if op == "a":
print("| Desayuno |")
print("|===============================|")
print("| A |Café |S/4.50|")
print("| B |Chocolate |S/5.00|")
print("| C |Jugo de Fresas |S/9.00|")
print("| D |Jugo de Papaya |S/8.00|")
print("| E |Pan con Pollo |S/7.00|")
print("| F |Pan con Jamón |S/7.00|")
print("| G |Pan con Tortilla |S/7.00|")
print("| J |========== SALIR ==========|")

while True:
des = input().lower()

if des not in ("a", "b", "c", "d", "e", "f", "g", "j"):
print("Opción inválida, ingrese nuevamente")
else:
break

if des == "a":
mnto = 4.50
imp = mnto * igv
totalfac += mnto + imp

elif des == "b":
mnto = 5.00
imp = mnto * igv
totalfac += mnto + imp

elif des == "c":
mnto = 9.00
imp = mnto * igv
totalfac += mnto + imp

elif des == "d":
mnto = 8.00
imp = mnto * igv
totalfac += mnto + imp

elif des == "e":
mnto = 7.00
imp = mnto * igv
totalfac += mnto + imp

elif des == "f":
mnto = 7.00
imp = mnto * igv
totalfac += mnto + imp

elif des == "g":
mnto = 7.00
imp = mnto * igv
totalfac += mnto + imp

elif op == "b":

print("| Almuerzo |")
print("|===============================|")
print("| A |Café |S/4.50|")
print("| B |Chocolate |S/5.00|")
print("| C |Jugo de Fresas |S/5.00|")
print("| D |Ensalada de Frutas |S/8.50|")
print("| E |Sándwich de Pollo |S/10.00|")
print("| F |Arroz Chaufa |S/12.50|")
print("| J |========== SALIR ==========|")

while True:
alm = input().lower()

if alm not in ("a", "b", "c", "d", "e", "f", "j"):
print("Opción inválida, ingrese nuevamente")

else:
break

if alm == "a":
mnto = 4.50
imp = mnto * igv
totalfac += mnto + imp

elif alm == "b":
mnto = 5.00
imp = mnto * igv
totalfac += mnto + imp

elif alm == "c":
mnto = 5.00
imp = mnto * igv
totalfac += mnto + imp

elif alm == "d":
mnto = 8.50
imp = mnto * igv
totalfac += mnto + imp

elif alm == "e":
mnto = 10.00
imp = mnto * igv
totalfac += mnto + imp

elif alm == "f":
mnto = 12.50
imp = mnto * igv
totalfac += mnto + imp

elif op == "c":

print("| Cena |")
print("|================================|")
print("| A |Café |S/7.50 |")
print("| B |Chocolate |S/9.00 |")
print("| C |Jugo de Fresas |S/10.00|")
print("| D |Ensalada de Frutas |S/11.50|")
print("| E |Sándwich de Pollo |S/10.00|")
print("| F |Arroz Chaufa |S/14.50|")
print("| J |========== SALIR ===========|")

while True:
cn = input().lower()

if cn not in ("a", "b", "c", "d", "e", "f", "j"):
print("Opción inválida, ingrese nuevamente")
else:
break

if cn == "a":
mnto = 7.50
imp = mnto * igv
totalfac += mnto + imp


elif cn == "b":
mnto = 9.00
imp = mnto * igv
totalfac += mnto + imp


elif cn == "c":
mnto = 10.00
imp = mnto * igv
totalfac += mnto + imp

elif cn == "d":
mnto = 11.50
imp = mnto * igv
totalfac += mnto + imp

elif cn == "e":
mnto = 10.00
imp = mnto * igv
totalfac += mnto + imp
elif cn == "f":
subtotal = 14.50
imp = mnto * igv
totalfac += mnto + imp

break
else:
print("Opción inválida, ingrese nuevamente\n")

Buenas tardes mi brou, si puedes vuelves a montar el codigo pero antes, de publicarlo hay una opcion que es </.codigo en el editor de texto, dale ahi para que te copie el formato