Sangeetha Mobiles — cheating offers

Address:

Chennai, Tamil Nadu

I purchased a Redmi Note 7 pro 64 gb mobile from sangeetha store in anna nagar. The price was quite high compared to online store.
Sales rep promised me that there is an offer 45th Anniversary by installing our mobile application in 5 working days, you will receive an offer to have more than 3000 rupee.
I trusted the sales rep head words and purchased the mobile.
I bought the mobile on 22/06/2019. but still now i couldn't find the offer for the phone purchase.
I came frequently to sangeetha store but they said me to wait for it & uninstall & reinstall the mobile application
I waited patiently for many days but now when i checked the mobile i couldn't find any offers except a thank you message. I am frustrated

Its a great cheating happened to me. i wasted my time & money to this.

I need necessary action to be taken and give back the 3000 offer money as been promised by Sales rep of sangeetha.