Opencart, how to display the user's full name when placing an order without registration?

Question

opencart

Hello!
There is a simple store on opencart 1.5 ..
It has a payment module through Avangard Bank.
It is necessary to make sure that the xml that flies to the Avangard bank contains the data of the full name, address, phone, email
I was able to transfer this data if the order is placed by a user registered on the site, everything is simple there ($this->data['firstname'] = $this->customer->getFirstName();).
But if the order is placed without registration, I don't know how to intercept these variables.