Having recently bought my S4 it has a vibration issue from the rear which gets worse at speed. Initially thought it was wheel balance as rear tyres had just been replaced. Had the wheel balance done on the rear and found there the nearside wheel was buckled. Bloke said no problem balanced the wheels and now have the vibration at lower sppeds too

.Took the car to Williams last friday who have replaced the buckled wheel and rebalanced the wheels and....only marginally better but they did find that there was a split on thge outer casing of the propshaft which could be the culprit

Any ideas welcomed. I'm still trying to master adding photo's so hopefully they are attached of the split propshaft.
Cheers