MTN Kolonade store incompetence

I am very disappointed at MTN Kolonade branch,I took my Sony Xperia XA2 to be changed because the speaker was not working properly it gave funny sounds when I was on a call.it has been a month now and I have been waiting for my a new phone but I have not received it, the agent assisted me to the best of her ability but the manager has failed to look at case and rush the process of me getting my phone cos now I am paying for a phone that I don't have,my business has been compromised because I strictly took a contract with the aim of transforming my business.I wouldn't advice anyone to trust that the store can come to their aid as they promise to.