A lot of complaints here in the US about this particular Onkyo receiver as well, check out Avforums.com and the customer reviews on amazon.com. Amazon.com is discounting its remaining units (12 as I type) to half price to shift them.
I bought an Onkyo TX-NR717, the next model up, in November, been using it since Chrimbo, and have had no problems whatsoever with it. It too was marked down by 50% from the magically-just-under $1000 US to the magically-just-under $500 (640-odd quid to 320-odd quid? - remember that in the US, sales tax, if payable, is added on top of this, so in the UK prices should be 20% higher, but no more except for the "rip-off Britain" factor)
Don't know if the 717 is sold in the UK or not, but I would suggest anyone thinking of the 616 should avoid it like the plague, stay off the curries for a couple of extra weeks and go for the 717 or 818.