As we register our mobile numbers and adharcard card or other documents with the bank they use them for unwanted calls and promotions by calling customers.  

They don't think that we are in a situation to attend call or not , we might sick ,sleeping, on rest ,driving ,but they call at any time without persons wish and after declining so many times .. 

We use credit cards and bank facilities for our convincing not to be harassed by call from them .