I'd be interested to hear how long you actually waited. I had a similar situation when BA diverted a MAN bound flight of mine to LBA. Again, we were all told a bus had been arranged but we had a near 2 hour wait and then the bus didn't have sufficient seats for everybody. The final straw came when we reached to outskirts of Manchester and the driver came on the microphone and asked if anybody knew the way to Manchester Airport!

If it happened to me again I would reluctantly just get a cab and take my chances with getting compensation.