i cant access my online account as i never set one up or used the sim card

I purchased a phone from the Carphone warehouse on an ID plan as it was the cheapest option.  I never however used the sim as the data plan was poor so purchased another sim with a better data plan to use with the phone.  The problem I now have is I cannot access an online account as I never set one up and I no longer have the sim card and I need to check when I can cancel the contract