Seat Altea whining noise like wheel bearing gone, getting louder

Certainly sounds like bearing . Not always play on bearing when it's knackered .Could spin wheel and probably feel roughness .

I had a whining groan from rear wheels on my 2005 Altea, which was since diagnosed ..see below. However this was only noticeable at very low speeds such as when approaching a roundabout, since the noise generated was not loud.
After lots of checking the rear wheel bearings, the problem was finally diagnosed as due to uneven rear tyre wear. The rear camber settings were miles out (apparently common on the Altea) and rear tyres were running/wearing on their inside edges, generating a low level whining noise.

Camber was corrected, and new tyres fitted. No more whining.

But it sounds like your problem may be louder.. Good luck