Timing belt changed, 2k miles later, belt broken because of "oil change frequency"

[SimplyComplex314]

Hey all. Sorry for the long story, but here we go.

So on my girlfriend's 2004 Aveo 1.6, we got the timing belt changed at 58xxx miles, because we know about the issues with the belts at around that mileage. We took it to a smaller local mechanic, who charged somewhere near $600 for the belt/water pump change. Everything was fine until the other day when the belt just snapped while I was driving it. The car immediately turned off, and I coasted to a parking lot. Had it towed to the mechanic who did the belt previously.

They've come back to us saying that the (new) timing belt broke because the oil wasn't changed enough. This has (apparently) caused the top camshaft to lock up and break the timing belt. Now, the cam wasn't locked up when I got there because the mechanic said he "already loosened the bolts holding it in place to get it moving again". I was looking at the head and it really didn't look awful, but it definitely did look as though there was black sludg-y oil build up around the bolts, but again, nothing terrible. They're quoting $850~ to replace the belt, some valves, and other minor stuff.

This is weird, because the 1.5 years that my girlfriend's owned it, we've kept up with oil changes very well. Never going over 3500 miles before a change. Mostly before then. Her brother had it for the 2 years before that, changing the oil every 90 days or 3k miles. Her grandfather (now deceased) owned it before that, and we honestly can't speak for whether or not he kept up with it. For the past 3-4 years, though, it's been well maintained.

This sounds to me like they either screwed up the belt change, or just didn't do it, and are now trying to cover their tracks and not have to fix this on their own.

Any advice or insight into this and what I can do/if this is a feasible situation that happened? Could the cam locking up from lack of oil changes (despite the fact that it's been very well maintained for at least the past 3 years) and break the timing belt? There's never been a check engine light or any weird issues leading up to this.

Any help would be appreciated. Thanks, all.

[Daox]

If the camshaft locked up you would need to replace the head as the cam journals would be ruined.

Did they replace the tensioner when they did the timing belt?

[AceAveo]

They've come back to us saying that the (new) timing belt broke because the oil wasn't changed enough.
This is weird, because the 1.5 years that my girlfriend's owned it, we've kept up with oil changes very well. Never going over 3500 miles before a change.

Well, then they're obviously feeding you a crock of B.S.. This is one reason why it's important to keep a record of all maintenance and receipts, it can easily be proven how often you've changed the oil. Their defense would crumble very quickly in the face of oil change receipts and odometer readings proving regular vehicle maintenance.