If a reboot does not bring the channel back then ring customer services. They should try sending signals to the box to refresh the NIT, which is the likely cause of 101 & 103 disappearing. Freesat satellite boxes also occasionally have this issue.
Cable customer since 1993. Services: FH TV, Sky Sports & Movies (2xV+), Talk Unlim Telco, VIVID 100, Virgin PAYG Mobile