Faulty product

Location/place: bangalore

Name of company/service: mts

I bought a MTS datacard on 31st July.When i checked,it was not getting detected on my laptop.I booked a compalint and received the reply that the issue will be resolved within a day.I waited for 2 more days and never got any reply.I went directly to the mts shop where i bought the same and told about the issue.The assured me that they will send the support engineer to resolve the same.I continously followed up and even went to the shop 5-6 times but they never gave a solution
and no support engineer came.Again on 10th august i went to the shop and wanted to return the product and get the money back.
They were not ready and again assured to solve the issue the same day.Noone came and agian on 13th august i went to the shop and returned the same and asked for the money back.They were not ready and told that once it is sold they’ll never return the money.Iam having the faulty card with me now and is of no use to me.Requesting you to consider the situation and take the necessary action
The shop details is as below:

Mts
Near cullapah circle
kammanahalli
bangalore 560033