Had new engine installed, now problems

In May I took car into shop due to it running horrible, they said I needed a new engine. In three and half months I've only had my car 9 days. It has been in and out of the shop since May. First time, after new engine, check engine light second day and hardly any power even with pedal to floor, back to shop. One month later I had it three days, A/C fluctuates, not very cold and check engine light on and blinking, back to shop. Again out of shop, same day runs terrible, back in shop. Again, check engine light day 2, I've been told causes were turbo wasn't plugged in, needed new a/c gasket, check engine light needed to be reset, fouled spark plug. I'm going to go take the car back today, day 2 out, it's still got no power, it sounds like you're going fast when pedal to floor, but it's struggling to hit 40 mph and check engine light again! Yes I'm being played, I can't take it anywhere else due to the lease plan, plus some of it is under warranty with new engine. They did charge me $900.00 for the fouled spark plug and according gasket, that took 34 days to fix. I'm wondering if all these issues are due to them being incompetent or is it just bad luck? Could the A/C be damaged during the new engine change? Spark plugs? Does it really take 1 1/2 no to change an engine? 34 days to fix a spark plug and a/c gasket? I'm female so I guess they are taking advantage of my lack of knowledge. Thank you for any suggestions, help.