Bajaj Finance — loan not getting auto-deducted

Address:

Mohali, Punjab, 160069

I have given all my documents eg. Cross cheque, account nubmer of the bank with each and every details but then also, i am receiving messages from bajaj that your amount is due for payment and when i checked the details in their website, it says "my given bank a/c doesn't exist". This is the consecutive 3rd month when i am receiving the threatening messages for payment of may said amount of 1875/-. I dropped an email to them but in vain.