My rear washer pump works and runs as you can hear it but all I get is spatters of rusty water... Any ideas?

Mine does this quite a lot. You need a pin to unblock the nozzles.

If you don't free up the water flow then the back pressure will pop off the tubes at one of many different weak points along its journey from the washer bottle, filling a part of your car up with screen wash (usually the spare wheel well or all over the CD multi-changer).

A common fault on the Octavia, a quick search will reveal plenty of threads, good luck

Cheers guys, I'll have a look later