Some credits can be reserved for a pending operation or protected for higher-priority number renewals. Total balance is therefore different from the amount available for a new start. A payment hold or monthly cap can also refuse the charge.
Check Usage, funding priorities, and the exact billing error. Do not change priorities simply to silence a warning without considering which numbers need protection. If the available amount cannot be explained, send support the time and redacted balance details. Re-pairing the number does not free a valid reservation or override funding rules.