Bosch Home India — Extended warranty receipt

I purchased a Bosch washing machine 4 month ago from a store in chennai. I was told the installation engineer will arrive the next day for installation and I can purhcase an extended warranty from him directly.
I paid the amount for the extended warranty to the engineer next day, he did not provied me a receipt, he said he will need to register it once he reaches office and I will be receiving an email with additional warranty information.

I've been reaching out since then, I'm not receiving a response from the service center nor the receipt

This is highly unacceptable. I'd like my issue rectified.