I would like to be able to sell blocks of repairs which would be purchased by client upfront. Then the client retains a credit for the denomination of units in the block purchase. This units would be deducted at time of use until insufficient credits remain.

some of the uses:
1) pre-selling billable hours
2) pre-selling bulk repairs (especially useful for lower cost repairs that individually are unattractive to sell/offer)

What this would require:
1) point credit system tracking (basic ability to add and subtract points)
2) point binning - ability to create point bins for different purposes categories
3) a way to create points with link to its specific bin from a purchase of a created inventory item.
4) a way to pay for a service using points with a designation of how many points that service will cost.

here is an example:

support hourly rate is $95 per hour. However, customer can purchase tiered blocks

buy 10 hours $750
buy 20 hours $1200
buy 30 hours $1500

each hour would be tracked as one credit assigned to bin "Hourly support".

customer purchases a single unit from inventory which triggers the action to add the respective credits to their point bin for "Hourly Support"

Now upon redemption for any new support tickets created the repairshopr app allows service provider to invoice for service hours and pay the bill from credits on clients account until insufficient funds are reached at which point normal billing would apply or the client could purchase additional blocks to top off.

The use and workflow for other services including those that require hardware are the same, even if hardware is included in the credit via using the bundle system as the item being charged and paid with credit/points.