How do a add a receiver with Card I bought through Ebay to my existing Direct TV account.

if you "BOUGHT" them --you can NOT add them to your account --the only way to add anything to your existing D*TV account is to order it from D*TV as all equipment is leased --NOT SOLD AS OWNED --in other words bought bricks 

Hope you haven't actually purchased those C61s yet. You won't be able to activate them on your account. Only boxes obtained from DirecTV can be added. 

DIRECTV over the phone activations with eBay equipment is a no-go. Also, if you decided to buy more than one Genie, that would not be possible because more than one Genie on an account does not work. As far as the C61 goes, I wouldn't be too surprised if someone over the live chat function is able to activate it for you. I always use live chat when activating receivers since anyone over the phone follows the rules and doesn't do it for you. If you actually bought the receivers and can't return them, give live chat online a chance and see if someone gets it activated for you. 

First of all, Mini Genies are not receivers. They are Clients. They have no tuners and cannot work by themselves.

Since launch of the original Genie, boxes are "lease" only. This means customers cannot transfer boxes between them or sell them. Those boxes are returned to DirecTV or recycled if too old a model.

As the Mini Genie Clients are C61, that is the most current regular model. That means they could be stolen, someone upset with DirecTV refuses to return and trying to get some money to cover (at least in part) their non-return fees, or the person didn't understand they were to be returned to begin with.

DirecTV activates receivers/clients from an official order. They also should activate boxes from an authorized 3rd party retailer, though that has seen issues recently.

Also, you say your service came with an HR54 but found the "same receiver". Accounts may only have one main Genie as works as a server. You cannot have multiple.

The Genie can pair with several Clients, but only 3 at most can be in use at one time. This is because the tuners are shared since Clients do not have their own. If your household has at least 5 TVs, then you need an HDDVR instead of a Client. Though even at 4 or less TVs, HDDVRs are still better than Clients since being dedicated receivers they have 2 tuners each as well as 500GB recording space (per most recent models).

Either you got scammed on eBay or the seller doesn't understand how it works.