Hi Folks, new to this so bear with me

I recently bought a 2015 A3 Sportback 1.6L Diesel and love every aspect of the car, bar an annoying, intermittent rattling sound emanating from the steering wheel. The only thing I can liken it to is a "sprung" sound and I have twice had the car in to Audi to check under the warranty. The second time, they advised that they simply added some adhesive tape within the cavity of the steering wheel trim to eliminate scope for play and advised that should sort the issue. Alas, the noise is still present and this has not worked.

Generally the vibration from the road brings out the noise when driving over uneven surfaces at relatively low speeds. Also, if you tap the steering wheel with a bit of force, this brings the noise out. I have attached a video clip, where you can hear the noise over my knocking of the wheel (pleas note it is not the banging noise but the sprung sound you can hear above that)

Bit of a strange one which is frustrating more than anything else, has anyone else experience this? Any help appreciated

Thanks in advance
Graham,
Falkirk, Scotland, UK