Technical Fuel injector problem

[faitpunto2013]

My petrol engine fiat Punto dynamic 2013 has mixed sound coming, went to garage and diagnosed and found to have the first fuel injector fault. I had tried more than three injector they didn't work...I tried by replacing the injector but found that new injector introducing to car didn't respond. I tried exchanging plug if to check whether plug may have fault but new injectors introduce to car doesn't respond. Is there any calibration method or I am doing something wrong. I am in Nepal and parts are very sparsely available.

 

[GrandePunto PL]

What kind of "garage" is it? Pro o amateur?

Maybe check the wiring first: plugs/sockets, wires, fuses, relays, ECU outputs (FES or MES program has a test option, you can switch ON/OFF almost all electrical equipment in the car, injectors, coils, fans, solenoids, lights). Your injectors wiring harness is a mess (someone has been there with insulation tape).
You can (you should) check the injector outside the car (basics using multimeter and power supply + compressed air).

These things above are very basics. No one should need internet for this (this is common sense, you just do it if you or mechanic from the garage have a clue about cars).