Airtel — sim deposit amount refund

Address:

SANKARI Salem dt, 637301

Hai my self muruganathan from Salem tamilnadu .
I have changed my postpaid SIM to prepaid number on march month .while changing to prepaid the showroom people replied the aim deposit amount will be sent to your home address through cheque payment .
For last six months I was keep on asking
And now in showroom they replied it's not relevent to them, call to customer care
Customer care is telling it's not refundable
I have changed two numbers and for each number I have paid 500 rs deposit but now they are telling no cash
Very nice service from Airtel