I am so disappointed

Iv wrote a review on August abt a phne that I took on contract with blue label connect. The phne goes blank immediately wen sum1 is calling I can even see who's calling sometimes it freezes the whole day no incoming or outgoing calls I use the phne for business so far I have lost 50%of my customers and I am paying 359 I logged the phone they came and took it n gave me the new phne doing exactly the same thing the phne is nt even 6 month2 weeks ago I lost I big gig because my customer cudnt get hold of me cz I cudnt ansa it ws freezing the whole day I called blue connect to cancel the contract and ask them to take the phne back I was told that they can cancel the contract but I have to pay R4000 rand my argument ws why would I pay the 4000 while it's them and their device who r failing me I dnt want the phne anymore all m asking is that its either they give me a Samsung or hauwei den I continue with the contract or we terminate the contract since dy say dy booked the phne again no 1 came to collect it and the manager comfirms that I'm nt the first person to complain abt this Ulelo phone he said they need to fix it 3 times bfre I get the new phne how abt the mney I lost and money I'm loosing on a process wen they took the phne it's nt 6 months but already I complained twice please assist