I've had 3 cases of Fan Belt breaking (all brand new) and one case of Generator Belt snapping due to timing seal leakage. I had the assembly taken apart and examined the pulley closely both the fan pulley and generator were in bad shape (lots of dents and sharp edges, which contributed to the breakage of fan belts every so often). I surveyed the Bilal Ganj market in Lahore and bought a good condition Kabuli Fan pulley for 350.-
However, the generator pulley was a different story, not only was it being sold for exorbitant prices, most pulleys I looked at were in even more worse condition than mine. Therefore, I decided to get it repaired from a kharaad shop, which did the job satisfactorily). Replaced the genuine Bando belts for both. Haven't faced the issue since then.
If you've never replaced a belt before and you're mileage has crossed 50k+, now's a good time to open the assembly and check the pulleys for any damage or fault, its a one time job only which will help eliminate or rule out any issues whatsoever regarding the pulley and will insure smooth operation of the belts (as they rarely break unless an issue like the one I had). Make sure that no oil is leaking directly on the belts themselves either, and if you notice any leakage whatsoever, get it fixed asap.