So I might be in the wrong area for this topic, so I apologize in advance because I'm a noob.

But heres my current problem:
The other day while I was driving in the rain, I noticed my check engine light came on and my speedometer started to fluctuate, so I pulled over and immediately turned off my car, and started it. It started up just fine with no hesitation. So I figured I would at least try to drive up the road to pull over onto a side road so I wasn't a traffic hazard. I pulled up about 300 yards, and I noticed that my car was struggling to accelerate and my speedometer was rapidly fluctuating, my lights were dimming. I pulled over onto a side road, had my car towed to a nearby mechanic. They called me on Monday to tell me that I needed a new alternator and battery, so I said fix it. Today, I went to pick the car up (after they closed and I had already paid them) and my check engine light was still on once I started my car. I didn't think much of it, considering they had said it was fixed. The moment I tried to accelerate, the car began to do the same thing all over again. I immediately turned around and dropped it back off.

So I guess what I'm looking for is some advice on what to do now, maybe some insight , or something. I've never experienced something like this before, nor have I ever had a problem with this particular mechanic in the past.

Thank you in advance.

 

Obviously they either didnt do the work as stated or messed it up or misdiagnosed the original problem.

 

Check your main grounds, batt. post and cable clamp, batt. to chassis and chassis to engine, DO NOT just eyeball them, disconnect/clean/reconnect. 94