Sounds like they've quoted for the entire L package.
Assuming you don't have a call package ATM, then going to L broadband (10Mb), L TV (100 channels) and L phone (unlimted evenings and weekends) would cost an extra £26.95 over the existing £11.99 you already pay for line rental.
L broadband added should cost £12.50 a month extra as Seb says. They have a promo for £5 a month for 3 months and £50 credit but I suspect that's for "new customers only"
but you've got room to haggle as you've been with them for what seems like an age.