Mobile operators are kind of old fashioned ISPs. They usually do not give fixed IP address to all their subscribers, because it would be too expensive and dimension-wise unnecessary. What they do is to assign a dynamic IP upon request by the mobile device. Depending on the size of the IP pools and their dimension/allocation it is perfectly possible that the 2 IP addresses are on the same network and in rare occasions to be even the same IP (of course, not used at the same time!).
So yes, it is quite possible that your deal was cancelled wrongly.
How are you going to prove that to Admin - I have no clue.
