Eircom mobile phone contracts

Hi,
Has anyone encountered difficulty with moving out of an eircom phone contract? They say that you can move in a set period of time. I did and now keep receiving bills. The last one was 500 euro. I am out of contract since December. I cancelled the account, they aggreed and cancelled direct debit.

Just to elaborate on this. It was with eircom mobile(business) I changed from another company. The eircom rep said that there was no problem moving back to original company and why not try it out, it would be more economical etc. Long story short. It was a disaster as the coverage was really bad and i needed the phone for business etc So i terminated contract.
The terms and conditions of contract were:"On expiry of the Term either party may terminate this Agreement on the giving of 30 days notice and, in the absence of such notice, this Agreement shall be deemed to continue on from month to month based on the Terms and Conditions herein. If the contract is terminated during the Minimum Period, you are liable to a termination charge calculated as the sum of the monthly Tariff Charges which would otherwise be payable until the end of the Minimum Period."
I terminated contract in December and have received 2 bills. The first one was 130. The last one was 540 euro. Although the bank has cancelled direct debit, they still taking money out of it.
Is this thes sum of the monthly tariff charges? It seems a lot? Any advice on this would be greatly appreciated.