Bajaj Finserv — misbehave of one of the employee

Address:

New Delhi, Delhi, 110043

I purchased a mobile handset and opted for bajaj finserv for financing purpose.
My bank account at the appropriate time had balance but the installment was not deducted from the balance
And now after somedays
Bajaj deducted the balance with penalty of rs 450 which is not acceptable
On calling one of your executive on his personal mobile no. He misbehaved and is not picking up the call again.
Kindly look into the matter as soon as possible.