Finally got it fixed, but took two trips to VW dealer.
Car went in and the front suspension link arms were replaced, car test driven by technician and signed off as ok, picked car up that evening and never even got onto main road before the knocking, banging started.
Returned to dealer who was a bit embarrassed to say the least, anyway got booked in for three days later and after test drive a different technician identified the noise was either rear shocks, rear top mounts or both.
Happy days the fault was near side rear shock and top mount, both replaced and car as good as new.
Thanks for initial replies even though it was a Polo.
Cheers
Mike