Adding Existing domain(multiple) to Microweber premium plan subscription

Yesterday i bought your hosting service of Premium Plan( monthly $5) for 1 year @ $60. But I did not get any invoice or any email confirmation of the purchase though the transaction notification mail from my bank says $60 has been given to Microweber. 

Now, I have multiple Domain which i want to add in this subscription. How do i do that. In reference to past conversation with you, i was assured that i can use multiple domain i.e. multiple online shop in a single subscription. 

Also, as the plan offers custom email address, I would like to request your instruction on how to get that service.

Regards,

Farabi