I purchased a car from them, it had a clean DEKRA report and was a gold sticker

I purchased a car from them, it had a clean DEKRA report and was a gold sticker. Few days after receiving the car, it had mechanical issues. I sent the car in, it's been 3 days since I sent it in and received no communication. Tried calling the call center 4 times in 1 day and still received no help.