Vodafone - Wrong Information

on **th Aug my Mom was travelling alone to Thailand, who was using my alternate vodafone number.So my brother called up vodafone and checked for the **hrs international roaming pack in which she could have free incoming/outgoing calls/sms and mobile data free for ***/-. so we activated the plan as suggested by them.And once she reached thailand i sent an email to deactivate the plan on toll free number.Now when i received the bill they charged me ****.**/- stating another plan should have been activated.
i activated the plan only after confirmation, i have activation and deactivation record.My credit limit was ****/- why that was exceeded without imitating me.International plan details not on bill.