Prepaid maintenance service

Hi all,

we often sell customers small “packets” of technical assistance hours. This is a kind of “prepaid” maintenance service where hours are dropped from the amount the customer has bought before. When the amount of hours achieve 0 we sell another packet of prepaid hours and so on.

What is the best way to manage this?

We already tried to activate stock for services, increase stock units (read hours in this context) but we didn’t find a way to decrease these via Tickets and/or Interventions. We also looked in Dolistore but we didn’t find a package suitable for the need.

Thank you very much for your help
(Dolibarr version: 11.0.2)