sadly i think it may be cause we live in the us and your in the uk (which i agree is total bull****) but may be a sad truth. just a thought, they got me my info on my rg170es in seconds. before i was off the phone i had the manual and wiring diagram before my vary eyes.
were you rude to them...
first off, are your audio cables near an outlet? you can get massive hum if they are too close and your cable is not shielded properly.
is the ground where you live or where your currently plugged into okay?
check the grounding on the amp cord the trace it to the internal for a look if/when...
did you try calling the number listed in contacts as customer service?
I just did about my rg170es and they sent me the schematics and the owners manual though the gentleman said they bought randall in the mid 90's so if it's old like mine then he called it a "hit or miss" situation.
hope...