The screen of my iPhone is not working correctly

If you're sure that nothing (case/cover, screen protector, dirt) interferes with your touch screen (remove any obstacles, if present), and if you already tried (to no avail) a "forced" restart of your SE 3rd gen, using these instructions: put it on charge for at least half an hour, then, keeping it plugged in, use these gestures:

Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the side (power) button. Only when the Apple logo appears (it might take 10-20 seconds), release that button (ignore all other screens that might appear, the one with the "slider" to turn the device off included).

If the issue still persists, it might be a hardware (screen? other internal component?) failure, and I suggest that you make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> https://locate.apple.com/choose-country-region . After checking it out, they'll give you all the available options.

Regards

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above;
• Using the "Apple Store" app, available and downloadable from AppStore.

Ever since the last update my iPhone did, the touch screen goes haywire whilst charging rendering the phone useless whilst on charge.

i have heard lots of comments about checking original cable (it is) and the correct plug (you no longer provide one) so whilst I can’t say the power outlet may be the cause, I find that very hard to believe when the phone worked perfectly on charge, with the same cable and power outlet, up until the most recent update.

I would be really interested to know how an update can change a power source?

It seems this is just a con to make you buy separate apple

power outlets!

not impressed in the slightest!