Late delivery for device that went to Huawei for screen repairs.

I have sent my device for screen repairs to Huawei via TNT courier company. A lady by the name of Charlene made a promise that my device will delivered to me within their turnaround time. Whenever I email them they always give me vague responses or worse ignore my emails. They strictly said my device will be delivered with their 7 to 21 days turnaround time. The manner in which they communicate with me leaves me with a lot of doubts and surely with the reviews I read about them makes me even more scarier. The responses are so vague.