Michael Koblic writes:

This time I found an item "consumables" amounting to about 10% of
the price.

That little dishonesty has been around for years. Maybe the economic
pressures of late have been making it appear more.

It's just small enough of an increment to avoid ticking off the average
customer so much that they won't actually dispute it.

Here in Florida we have a special courtroom at the county courthouse
where you can get your car back by court order, the same day in a
dispute with a repair shop, as long as you agree to have the case
decided by the judge. I've never had to invoke that, but this sort of
nickel-dime thing (I guess that would be $1-$5 thing in today's inflated
money) would have me considering it.

Any repair and service biz is a classic case of "information asymmetry",
with regards to tricks played against the consumer. They experts at
practicing the scam, you're just an occasional amateur stumbling into
their expertise.