1/ 18 month lock-in (even if you already have a phone) - Why? BT are even doing this now!
12 month contracts weren't deemed as profitable enough, at a guess. Also, it makes people less likely to chase an immediate upgrade, as they can't remember exactly when they're due! If you already have a phone, you should be getting a significant discount on your monthly rental in lieu of a handset.
2/ Random prices - Do you know ANYONE who is paying the same price? They seem to make the prices up depending on who you are and who you talk to when you subscribe
I think it depends on what offers / price plans are currently available when you subscribe! There are at least 3 different versions of the Flext £180 price plan that I'm on; the original one, the one I put my then gf on to which didn't include voicemail, and the one I'm currently on (Flext 2009) which includes free Web n Walk and some 0800/0845 numbers.
3/ Charging for 0800 and 0845 numbers - Why don't these get included in your free minutes?
Because they're not free to the telco, and thus have to be factored in to the profitability model somewhere. Newer price plans are including some of these as part of the deal e.g. Flext 2009. However, as a trade off you might find you lose something else, e.g. only £175 worth of "credit" instead of £180.
4/ Marketing texts from the operator, which they generally stop after you have told them a dozen times not to send you any more
As soon as you get one, reply (for free IIRC) with the word STOP and nothing else. That should pretty much deal with them. The problem is, when you call a CSA and ask them to update the main system, it probably doesn't get reflected in any advertising promotions until Marketing update their lists in 3 months time :/
Disclaimer: No I don't work for them.