What Would You Do In This Scenario?

[Casandra M.]

I'll keep it short:

We put a used stove in a tenant's unit.

Tenant complains the stove will not heat to more than 350 degrees.

We decide to send a repairman over because these tenants have been high maintenance and we want to minimize contact with them beyond what is necessary for our immediate response. 

Repairman calls me telling me that the stove works, the issue is that the tenant didn't know there was a preheat time difference between gas stoves (what she's used to), and electric stoves (the previous and new stove in the unit). So, after 10 minutes of preheating, the stove wouldn't be 425/450 or whatever she was setting it to, because it wasn't preheated enough.

Would you charge the tenant the repairman's bill for his base visit cost, or should we eat the cost because we chose to not go over and test what she was claiming, before we called in a repairman?