Hi martyn24,
We see you receive a message that you do not have enough credit when attempting to place a FaceTime call.
To aid us in isolating this, is this message from your carrier? Apple would not monitor or cut off cellular data or credit. That would be through the carrier with which you use your iPhone.
As to why you're receiving the message, can you clarify the following?
- How are you placing the call? Are you going into the FaceTime app directly, or by clicking on a recent contact?
- If you take a look at the Recents section of the Phone app, do you see "FaceTime Video" or "FaceTime Audio" below the contact?
We ask as if a cellular call is being selected and there is not enough credit on the account, that may explain the message. As FaceTime may have access to your cellular data, you can ensure FaceTime is only using Wi-Fi by toggling off the FaceTime option under Settings > Cellular.
See more info about calling via FaceTime in the article below, and feel free to reach back out with the additional details we'd need if you have further issues.
Cheers!