Car Toys

On Saturday we took our 2019 Nissan to have some cool stuff put in our car, new stereo, speakers, tinted windows and auto start with the alarm. We left and went home expecting to pick up our car on Sunday afternoon sometime. Well Sunday came we went to pick up the car, it will not start or run. The tech was thrown and confused as he just had it started, when we arrived it was in the area where they do the work. My husband finished up and then went to leave. The car would not engage or start. So, I then picked my husband up and we were told it would be completed by Monday night, and we would get a call. Well, no one ever called, so at about 430 pm I called and was told they do not know what is wrong with the car and they needed more time. I was told I would be called to be let known what is happening, well, I still never got that call. I have had to call each time, and still not getting any answers. I have called back today which is Wednesday, and day 5 of no car. I was told they still do not know what is wrong with it or how to fix it, and we were offered a rental car, we accept a rental car but was told there are none. I called several in the area and they all have cars to be rented out, so I feel like we are being lied too and being taken advantage of. My car is broken when it was absolutely fine when it went into the shop, it was only due for its regular oil change. I would like to talk with someone to answer my questions and to find out who is paying for my car?