XO Ethernet Circuits Can't Have Bandwidth Upgraded?

Anyone with XO circuits out there that can lend a hand here?

We have an XO circuit through one of our vendors. We have no business relationship with XO at all and this is an unmanaged circuit we use to communicate with the vendor.

The handoff is copper Ethernet and I do not know the hardware involved as it comes in over a cross connect to our rack. The circuit has 2 VLANs, one with a public internet IP and one with a private IP to use to communicate with the vendor. We had XO shut off the public VLAN so the circuit couldn't be DDOSed and so the circuit appears to be a private layer 2 connection between us and the vendor.

We currently wish to double the bandwidth of the circuit, and we will still be well below the 100Mbps that the port is.

We're being told this is impossible and we must order a new circuit and term the old one.

Can anyone confirm if this is accurate or if it's complete bullshit? We've never had an issue with any other network provider adjusting the traffic policer on our circuits to adjust bandwidth when upgrading a circuit. Level 3, AT&T, Comcast, etc. Usually 1 phone call / change order is all it takes to have them adjust the bandwidth on the circuit for us. I stumbled across XO's Bandwidth-on-Demand service, but have no way of determining if it's applicable to this circuit.

Since we're not an XO customer our argument isn't with them, but the vendor that's passing along this information to us.

Thanks