...make sure you ring them up every few months (150 free) and check you are getting the best deal.
I rang them today as my pack was costing me £61 p/m
extra standard box
after saying I wasn't happy and thought I was paying too much, 5 mins later it will now cost me £49.36 p/m
More than £11 off a month
So if you haven't checked for a while. give them a ring.