Ackermans Premio S87 malfunction

Hi I bought a phone(Premio S87) by Ackermans(Virginia) beginning of February. 2 weeks later (16 February)went back to let them know the phone is super slow, it has touch screen problems also does not allow me to answer calls while on other apps, It does not even show who is calling. It goes blank but still ringing. They took it and told me they should send it back it will be back after three weeks. I only got it 4 weeks later. They gave a new phone but it is still giving me problems the answering of calls is still a problem. It is still going blank on the screen still ringing and unable to see who is calling. It only shows after a minute or 2 who called. I missed an important call because of this malfunction. I am so disappointed I'm not sure what to now if they book it again I will be without a phone again for weeks again.