Im having an odd issue with my ISP (COMX.dk)

I have a managed access gateway box (Telsay) with three 8P8C ports for use with Internet and Ip-Tv (respectively on different VLANS (so does my ISP tell me))

To utilize a port you will need to register your device's mac address through an online interface. You will then get your device paired with a static ip.

I am using one port actively and I have registered another device (router). The router is configured to listen for an active dhcpd on the network.

When my router get a lease I get a private ip 192.168.2.2 (not the one bound to my mac) which is odd! I unconnected my router from the gateway and connected my laptop directly. Same thing happened - I was given a private address. I did a port scan on the gateway and found port 80 to be open and browsed to the ip. I was then presented with a management interface of a Belkin wireless router (HMMM!!!!) <--by the way, not my gear

At this point I called the ISP to let them know of my issue/findings - Only to be replied "Well, we cant see any rogue dhcp servers" (thinking to myself, well I can)

I then decided that it could be fun to try the other port of my gateway, only to experience the same. So I reconnected my router and used the remaining port to make an observer(wireshark promic etc.)

I am able to see my router trying to discover a dhcp server but I can also see my ISP's IGMP and PIMv2 packages just repeating the same pattern. Hello...Hello...Hello :)

So I called them again, only to get the same response, "we dont see any rogue dhcp's...we cant see the host you are talking to (mac address of the Belkin router)...you are definitively connected through wireless?!?(no im not, no such thing as a wireless wire - i thought to myself)"

My questions is,

What is going on? (besides from what im reporting here) What am I seeing that the don't? What can I tell them in order for them to resolve mine/their issue?