HDFC Bank — Issue regarding UPI transactions

I have been using HDFC UPI payments via GooglePay, PhonePe since 1 year. Recently, On 31st Jan I did my last transaction with a merchant account. Later, that evening I am not able to do any UPI transactions as it is stating "Your mobile number registered at the bank is different from the number verified on Google Pay". I am able to receive money but not able to send. As per HDFC bank employees said my UPI transactions are blocked. I am not aware of how to unblock UPI. Could you please help me on that.