Horrid experience after service!!!

Took my car for a service on the 14th December 2023. Collected my car on the same day and on Friday the 15th I started noticing a weird noise coming the engine. I called Haval Midrand to report the issue and they advised me to bring in the car on Wednesday the 20th. After one of the technicians had a look in the engine, he tells he suspects the catalytic converter is “missing” and asked me to where do I park my car. So I could leave the car on the said day because I had an arrangement I had to attend and I can only bring it on Friday the 22nd. Today they confirmed that it is indeed “missing”. I was shocked!! They are coming up with theories of how the component could have been “******” in places I have been to. This is ridiculous!!! I have been driving the Haval H6 for 1 year and have never had any issues until it came from service. One of the managers called me and asked that I bring the car in on the 2nd of January. Nothing have been done. I was then called by Selwyn who initially sounded like he was going to resolve the issue by nothing has happened. I am at a crossroads.