I use skype and have never had a problem. It is free if you use it Skype to Skype calling. If you use it to call landlines or mobile phones there is a charge for it thats why you have to enter your credit card number when you use features that arent free it is consiedered skype credit or you can buy a monthly subsription . Stop using it to call landlines or mobile phones. You need to read the fair usage policy.
Calls to phones and mobiles and Skype To Go* calls are included in your subscription subject to a fair usage limit of 10,000 minutes per user per month, with a maximum of 6 hours per day. Also, no more than 50 different numbers in total can be called per day. If your subscription includes more than one country, then this is the total amount of minutes allowed per month on your account, and is not a separate limit for each country.
Once these limits are exceeded Skype will charge normal rates and a connection fee for any additional minutes used. Subscriptions are for individual use only. Each subscription is to be used by one person only and is not to be shared with any other user (whether via a PBX, call centre, computer or any other means).
*The rates charged by your operator for calling your Skype To Go number are not included in your subscription, and are always payable by you.
If your subscription includes any of the following countries, calls to both landlines (excluding special, premium, service and non-geographic numbers) and mobiles, are included, subject to the fair usage limit above:
- Canada
- China
- Hong Kong
- Singapore
- Thailand
- United States
If your subscription includes any of the following countries, calls to landlines only are included (excluding special, premium, service and non-geographic numbers), subject to the fair usage limit above:
- Argentina
- Australia
- Belgium
- Bulgaria
- Chile
- Colombia
- Croatia
- Czech Republic
- Denmark
- Estonia
- Finland
- France
- Germany
- Greece
- Guam
- Hungary
- Ireland
- Israel
- Italy
- Japan
- Korea, Republic of
- Luxembourg
- Malaysia
- Mexico - Mexico City, Guadalajara and Monterrey only
- Netherlands
- New Zealand
- Norway
- Poland
- Portugal
- Puerto Rico
- Russia - Moscow and St. Petersburg only
- Slovakia
- Spain
- Sweden
- Switzerland
- Taiwan
- United Kingdom
Skype reserves the right to change this fair usage policy at any time. Changes shall become effective within thirty (30) days of publication of the revised version on www.Skype.com. Your continued use of your subscription after expiry of the 30-day period shall constitute your acceptance to be bound by the terms and conditions of the revised fair usage policy.
What it sounds like to me is you used a service that wasnt covered under your subscription policy or outside the parameters of it. So they will charge you everytime you do it. Go to the website and read it carefully.