The never ending lacking of service

I paid for the battery of my phone to be replaced on the 26th July. I didn't receive the phone back or feedback on when it would be ready. I chatted to their service centre via their website multiple times, they promised to get back to me and never did. Finally I complained on their facebook page, they asked me to email ********** I did this on the 23rd August. They rep**** to say they would get back to me and its the 13th September and still no phone or feedback on when it will be delivered. It's unbelievably poor service.