Mercedes. Changing my mind

I bought an old W203 c220cdi because I really loved the brand and have had a myriad of problems with it but the worst part is ordering parts. I am still waiting for a part that was ordered a month ago. The consultant had no clue what the part was. I had to go online and find the part number myself then take pics with measurements to show them. Its horrible service on a level I can't comprehend.