Nightmare toff!! At least it's raining down here at the moment, so I'm not THAT bothered today
Bri - I think there's something amiss for sure, but I never hold any car on full lock for that reason so I'm not sure it could be that...
Thing is, if there was too much pressure, I would have expected it to blow one of the push fit hoses before it popped the pump. Thinking about it though, there arent any on the low pressure side

You may be on to something there!!
I'll go down to the place I got the rack from tomorrow lunchtime and explain the situation - the pump didn't have any issues before I fitted the new rack - the two have to be related IMO
Cheers!!
Neil.