Opel Frontera Roof Cracked After Purchase And Replacement Request Denied

I bought an Opel Frontera in September and about one month after purchase we noticed that the ceiling of the vehicle was cracked. Because of this serious defect, we delivered the vehicle in October to the authorized Opel Mar service in Istanbul. After examining the vehicle, we requested a vehicle replacement, as such a problem in a newly purchased car is not acceptable to us. However, our request for replacement was not accepted by the authorized service. I request that my vehicle, which developed a cracked ceiling shortly after purchase, be replaced with a new, fault-free vehicle. I kindly ask Opel to reassess my case and provide a fair solution through vehicle replacement.