Customer Service and a useless phone

I bought a cellphone from Ackermans (Hisense) and since it has been giving me problems. I had to return it to the store for repairs but still it does the samething. It freezes and when you press five, you will see 7 , the battery and i loose my contacts. It hasn't been fixed yet. I really don't know what to do because it is a new phone. What i want right now is my money or any other brand beside Hisense. Please someone better contact me before i take further steps. That is my money we are talking about please.