Just had the same issue.
Spoke to them on Whatsapp and then two levels of customer service over the phone. Firstly they tried relentlessly to upsell us the normal TV package. When they accepted defeat on that they then said that yes the Stream box was free (as per the T&Cs) but that our broadband package would need to increase in price from £25 a month to £50 a month as they needed to 'rebundle' - so the stream box wasn't free, it was an additional £25 per month.
Finally got through to the third level who agreed that it should be free to add on the stream box and that we would not lose the existing discount on our package. However, because we were on an 'old' deal (despite renewing less than one month ago), the base price of the broadband had been increased so the package would still go up to £31 per month. So again, not free but an increase of £6 per month.
We met all the eligibility criteria and the T&Cs explicitly say the stream box is at no additional charge per month, just the one-off £35 activation fee and then the service (TNT Sports, Sky sports, etc) that you chose to add on 30-day rolling contracts.
This is frankly false advertising and I reported them to the ASA.
