Just a further update on my mum's '04' plate honda Jazz, after the transmission oil was changed under warranty back in March of this year, the vibrations stopped once it was carried out. However, the vibrations started to come back after a few months, and my mum has put up with it up until now without telling me.
I borrowed the car whilst she was away on holiday, and the vibrations was more than twice as bad now, it would vibrate between 10-20mph under accelleration, so I went back to Honda to see if they would honour the extended 7 years warranty on the CVT transmission, as the car was on an '04' plate and had only covered 40k miles. The guy behind the service desk knew immediately what I was on about, he sent an engineer to testdrive the Jazz to confirm it - all he did was do a brisk pull off in the car park, then parked it up! - and he said yes, that's a common problem, we will order the part for you to get it repaired asap.
So now waiting for the call for the parts to arrive so I can take the Honda Jazz to be fixed.