Mercedes-Benz of Walnut Creek

We purchased the vehicle, signed the paperwork and paid for it on May 4, Saturday. Everything was checked accdg to the papers. But when we got home, we noticed there’s an oil leak. We brought it back right away and they had to fix it. It took more than 1 week to have it fixed. We got the car on 5/14. Then we got a text again the following day that they forgot to attach or put back one of the car parts. My husband has to drive back and have it fixed again. It’s just an inconvenient because my husband is working and we already paid for the car and was not able to use it for 11 days. I am not sure what the process is for thoroughly checking the car before selling it. We just have a bad and frustrating experience.