The upgrade credit will not work if the product is already discounted.

There's no discount on it either.

It was there a few days ago and working. Then I get the money to pay for it and it's not working.

I just selected to upgrade a product and when I proceed to the checkout the upgrade credit is not showing either.

Therefore, I agree the website is currently having issues.

Your best option is to contact the Sales Team, although their hours are Monday - Saturday 9am - 5pm

Yup - I had the same problem and contacted sales. 
 

Annoying because I note the Beam gen2 has just gone up £50 in the UK website overnight - wiping out any 15% saving!!!!

That's what I wanted to buy as well. Typical.

OK - so, I’ve heard from Sales and they recognise there is an integration problem on the UK website, and they were willing to proceed over the phone. As the price had gone up of the Beam#2 over the w/e I had bought elsewhere more cheaply anyway. So my upgrade credit can be saved for Sub mini (when funds allow!).

It’s all back - credit showing now.

Yes, credit now showing, although I still get website errors browsing the Shop using Safari. Works fine on Chrome however.

Yeah I am in the UK and it doesn't work correctly another infuriating experience - I had not contacted Sonos for 10 years - now I Know why……………...

I’ve just checked again, and it’s working for me OK.

What exactly is not working?