The bc voucher you download specifically states that it is nit valid when used in conjunction with online codes. It IS valid in conjunction with online general sales.
You can’t use the bc voucher online, you need to reserve and collect and pay in store, which only works with in stock items, not models they have to ‘ship to store’.
NUS codes havent been working for me the last couple of months.
I got a team cx when they had 70 quid off all bikes over 700, then reserved a bike in store (had to play around with postcodes to find a store with physical stock), used the bc voucher instore for extra 10% off, then had registered my card with quidco to get 4.5 % cashback which has been confirmed on email.
They seem to have clamped down on exploiting the system!