Had oil and filter changed on my b8 2.0 tdi avant. Car has developed a knock under acceleration. Any ideas?? 

There could be a number of reasons for a sudden onset of knocking after an oil change. One could be that the wrong viscosity or spec. oil was used. Another reason could be that the oil filter collapsed, or if a cartridge type filter, it was put in backwards. This could reduce your oil pressure to the point it causes knocking. The most nefarious reason is that during the last oil change someone added something to mask a knocking condition. When the oil was changed, the additive was drained and the knocking started again. This is sometimes seen when someone is trying to unload a defective vehicle on an unsuspecting buyer. Best to have a competent mechanic diagnose the reason for the knocking.