Motor Village Portugal - Faturas erradas. bad service of oficina

hello, i have 3 Fiat tipo . i always repaired from motorvillage workshop. but this time i noticed they over charged the bills. i had same repairing of 2 different cars. i paid 409,47 euros for repairing for 1st car. next day i went to repair for 2nd car with same repairing and bill was 270,30 . when i noticed a 139,17 euros difference with same work. i protested there that same work with 2 different payments. they explained me that 1st bill we issued wrong . we forgot to add discounts of tvde. we will contact you and return but after long wait no body contacted me . i am attaching both bills. actually different receptionist issue different bills. be aware about bills errors.