Hi, I had exactly the same issue with my XC60 but the third time the belt broke it took out the cambelt and trashed the engine!
The car had always been serviced by main dealers and the belts and tensioners replaced in accordance with schedules.
The local dealer submitted a request for a goodwill gesture from Volvo but VCUK made no offer of support at all, in fact their responses were abysmal and quite insulting given I am a multiple Volvo owner.
Read all about my case here
https://twitter.com/CarComplaintsUK
Vehicle History (all work done by Volvo)
Feb 2017 Aux belt/tensioner failed & replaced
Jan 2021 Timing & Aux belts/tensioners replaced
April 2022 Dealer Service
July 2022 Aux belt failed replaced
April 2023 Dealer Service
May 2023 Aux belt failed after 9,827 miles loss of drive.
Be interested in hearing how you get on and happy to share the VCUK correspondence if it is any help.
Martin