The guarantee option, a sore subject for sellers, an outright license to scam for some buyers. Too many users started abusing this option, too many sellers entered tickets every time a buyer used it.
We played around with several solutions from turning the guarantee into a simple reject to allow the seller to "approve" any guarantee. They all caused problems and didn't provide a solution, so we've removed it completely.
Any order that had it enabled will keep it enabled. The feature has been disabled for all services and is not available on edit or creation of services.