My car has got wavy on the back actually dangerous wavy, is it a wheel bearing or axle bushing can anyone shine any light on this.

A punctured tyre?

Could be something as simple as the tyre pressures. If one or both of the tyres is under inflated, it can cause the symptoms you describe.

Get down and look at the inside edges of the rear tyres , definately check tyre pressures, a bearing that bad would be very noisy.

Broken spring?

Bush?