Pathetic Cutomer Service

Bought a Nokia 3 cellphone in March. Returned in July - they sent it in for repairs and gave it back to me. Upon receiveing the phone from repairs, it was still doing the same things - ringing and screen locked, cant screenshot, apps close and open on their own - phone numbers disappearing from the phone. I went back in after 3 days and i forced them to replace the phone - which they did. Two - three weeks later - this new phone has all sorts of problems. I use this phone for business purposes and it is making me look so unprofessional because I cannot utilize it properly to get back to customers. I am STILL waiting for Feedback from JET and their head office as they say they wont giive me a refund. I dont want this phone - either the phone is a fault - or JET is selling GREY products.Still having no joy with them after numerous visits to the store and emails and calls to their head office which arent even prepared to get involved.