Xiaomi India — i haven't received invoice for the mi earphone basic (black) which i have purchased

Address:

tilak nagar, gokulpeth, Nagpur, Maharashtra, 440010

I have purchased the mi earphones on 22nd jan 2020 from one of your franchise located in gokulpeth nagpur. But they still haven't mailed me the invoice nor they have given me the hard copy. It's been very disappointing experience for me.
I haven't seen such an irresponsible staff of any brand
I suggest mi that you should look after standardising your service aspects
It's been more than 14 days and i haven't got my invoice of purchase
Being one of the loyal customer this was an unexpected behaviour from your staff.
Also i would like to suggest you that those earphones aren't much comfortable to wear so you people should come up with some redesign for this product