Why does my replaced battery get HOT?

After years I busted my screen. I took it to local tech guys store. (reputable I am told) and they agreed to replace and suggested I change the battery also. They could see in the phone it was not holding charge. I agreed. I dont want a new phone I am afraid to loose messages in this one from my fiance that was killed last year. Screen changed and battery. Phone gets hot. Phone does whatever it wants on screen. I have no control. I went back. they said bad screen. replaced screen again. Few days later I go back because Phone is getting very hot and stops working correctly. They said bad battery. But to be sure they changed the screen again also. Phone still gets HOT and wont charge except on one charger at home. Which does me NO good since i drive and take pictures all day for my job, also requiring to run gps. Kills phone quickly.

They have already told me each time its the board that is now bad.

I hate NO problems before. Question WHAT DO I DO??

Should I get a refund ? Its going to cost me $250.00 to get new phone. I paid that for repairs.