Firstly I'd like to welcome you to the forums, and say that I'm really sorry to hear that you have two issues with your phone line, the charge for a call and the fact that your line currently has no dial tone.
I've run some checks on the line, and can see no reason why you should be experiencing a fault at the moment, however the test is currently showing that the line currently appears to be engaged. I'd now have to ask if you've been able to try another phone on the line, as it appears that something is keeping the line active, this would normally be a phone issue.
It may also explain the charge on the account, as although calls to landlines would be free at the weekend, they would be subject to a 60 minute limit, you can hang up and make another call which would be great, however if the call goes over 60 minutes, you would see a charge, and if there is something plugged in on the line that is keeping the line open, then this could well be the reason.
If you've been able to eliminate the phone from being at fault, then a technician would need to call out and investigate further. I've sent you a private message in order to set the wheels in motion once you can confirm that the phone has been eliminated. Please look to the top right of this page where you'll see a purple envelope icon, click on this and you'll see my message.