Electrical Problem or should I just ditch my 2004 Aveo with 263,000 miles?

I have a problem that started with an electrical issue. Power Window would not work and was blowing the fuse everytime I used the Drivers side window. Mechanic said it needed a Wiring harness and a fuse box that is located in the engine compartment. Well they couldn't find a harness so they decided to rewire it without the harness. (forgot to say the ONLY issue I had was the Power Window Fuse kept blowing,everything else worked fine) I got my car back and the A/C didn't work. that was fine because my window now worked. Well a few days later my window fuse blew again but my A/C worked now. Well I replaced the power window fuse and the window worked but my A/C wouldn't work again so back to the Mechanic I go. They say it is the computer so now I get hosed for a new computer. Oh and by the way my gas gauge didn't work after the rewiring and I have a check engine light on. so the other day (After 3 Months) I'm at a red light and all of a sudden the engine started to buck and the check engine light starts blinking......Well back to the Mechanic. They Replaced a Sensor and the car worked fine until after about 20 minutes of driving Check engine light starts blinking and the engine sounds like a motor boat.I also need to mention that because I don't have a fuel gauge the fuel light went on and I think I only had maybe 1 gallon left in the tank just before this occurred ..... So Once again back to the Mechanic.......Now they tell me that there are codes being spit out from the Fuel Sending unit to a transmission problem and he tells me that it is not worth putting any more money into the car. My Question is......Could all these problems come from the rewiring of the Door and the fuse box? Or do I need to take my Aveo with 263,000 mile on it out in the back and put it down? I was seriously thinking about getting a remanufactured engine (Not a rebuilt engine). Now I am really leaning towards scrapping my aveo for another vehicle.....Anyone have any suggestions? I need help fast.

#1 Find yourself a new shop/mechanic.
If you are thinking of keeping this vehicle, then you will need to decide whether it is worth putting additional $ into it, keeping in mind that your mechanic may have induced additional issues (as you said your original problem was just the driver window blowing a fuse). This is not to say that additional problems have not krept into the equation, but you have worse electrical issues than from your original first visit.
#2 Research your issue before bringing your car to a shop (you don’t need to know all the details on every repair, but it will allow you to ask pertinent questions), why are we replacing the computer when we have a door lock issue, and since I have additional problems. This site has a great deal of info.
#3 Ask for a detailed description of the repairs, including a breakdown of parts and labor, any reputable shop will give you this info.
Ask for the old parts to be returned, so you can have them looked at by your mechanic who replaced them a year ago(la lie of course) but may save you from some BS work that never gets completed.

Rightfully, you should be able to go back to the shop that ‘may have’ induced these additional issues, but actually you should find a reputable shop to do this if you decide to keep the vehicle. If you do so, make a detailed history of the previous work performed for the next technician.

just my 2. Cents, I hate seeing shops take advantage of customers.

Cheers