IMHO, anyone who rides should be enough of a wrench to fix flats. It's just faster and easier than visiting an LBS for that.

Sounds like a repeating problem, so look for something imbedded in the tire that punctures the tube. Wire segments from car tire belting are the usual suspect. They can be almost invisible, so look for clues like the tube being punctured in roughly the same position on the rim. You can do things like rub a cotton ball around the tire....where a few cotton threads get caught and remain is where the offending piece is located. Push the wire or glass piece out of the tire, then repair the tube and re-install. You may need to patch the tire on the inside if the hole has become big enough.

Not too hard, certainly easier than boning around at the LBS for that. Flats are part of life, resign yourself to accepting and repairing them. A patch kit costs <$5 and will fix a dozen flats, at least. Can't go to the LBS once for that much.