Honor 90 malfunctioning

I bought honor 90 month end of May at Mt Wonder park store, it started having problems in a months time, it switched off on its own, it jams, closes apps. Restarts itself more than 15 times in a day. Force closes apps, at times it doesn't wanna open apps and camera, it just goes blank. I discussed with the store and the phone was taken back for assessment, unfortunately they said there is no fault I need to update the software, which I struggled for days to do it and it's data consuming. After a day of updating the system, the phone started again with the same problem, but worse this time. Even when the phone is just sitting by the table, you would just see it going off or restarting itself and then it requires a pin the screen is jammed, it doesn't press and it goes off again. This is a contract phone, I can't continously pay for a product I'm not happy with and it's only 4 months with this phone. Honor must fix their software problems. If possible I would like to return this phone for another device, but otherwise I am a frustrated customer, looking at this phone everyday gives me depression. I would be happy if Honor comes back to me for assistance