The Steam Packet says it'll have extra staff on hand on Monday as it resells TT tickets that haven't been fully paid off.
On Facebook, the company says any festival bookings cancelled after balances weren't paid will be sold from 8.30am.
It says it's expecting high demand and additional staff will help with the expected high volume of phone enquiries.
Meanwhile, those trying to book online through its website will be placed in a virtual queue.
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