Charging Port, Face ID, and Screen Issues.

I’ve had this phone for a little over a year and a half, the first week of owning this phone I took it to the “Genius” Bar at a local store, guy looked at my phone and told me it was a bad motherboard and it was over $1,000 to fix it. It was within 90 days so they replaced the phone (Should of been a red flag right then and there), after I got the phone paid off my charging port failed, I’ve taken it to be cleaned, I’ve cleaned it myself, I’ve even used low amounts of nitrogen to blow the port out. No Avail I’m stuck using a wireless charger, next my Face ID went out and it no longer registers my face, no worries I didn’t like that functionality to much I guess, next my screen stopped responding, it would type E/R/D/X, problematic but I can use the phones left and right handed keyboard to bypass it a bit, now the phone screen *sometimes* registers my touch in all functionality. I talked to Apple on the phone and it really got me heated up, I laughed at the lady on the phone and said “I imagine you guys just follow a flowchart of diagnosis with no actual knowledge and when a problem falls out of the flow chart its time for a new phone” and she reassured me how great and qualified their training was, I said, “I can only imagine getting this actually fixed will cost me the equalivant of brand new phones” She then told me the price of JUST replacing my charging port will be equal or greater to buying a new phone. So while I wait and simmer in anger and see when the new Galaxy comes out. What’s the best repair options? I’m sick and tired of seeing a $24.99 part being sold for $1000. I’m in the HVAC/R Business and I understand how business costs work and how you have to set a certain percentage to be profitable in the parts, but a 3900% increase is robbery. How can I get into fixing Iphones? What are the best toolkits? Books? I have knowledge on soldering, wiring, circuit board functionality, can read a volt meter and understand ohm’s law.