Promotion code not working at checkout

I've been looking to purchase new broadband and have recently settled on a potential virgin one especially due to a promotion code that was given to me over text with £50 taken off the bundle. The promo code doesn't seem to work unfortunately. I was then sent a different £50 off my order, this time in link form, but this doesn't work either. Is there any way to remedy this? Neither offered promo code works.