If you ask the driver, I think they have to print you a voucher for completing your journey.
I got one the other day after a bus I was on stopped, apparently due to a problem with the suspension.
Incidentally on that occasion all the passengers were sat on the bus for about 5 mins not realising that there was a problem with the bus...as the driver hadn't bothered to tell us.
Is there some sort of policy against drivers talking to passengers using the mic/speaker system?