Vat!!

[Bilbo]

I really wish o2 would tell you there’s £4 on top of tariff price it’s so annoying 

[pgn · Accepted solution]

They do include VAT in the selling pitch if it's a consumer tariff, but may not if you are on a business tariff.

Some trusted partners call you with great offers, but only because they do not add VAT at 20% to the figures, misleadingly.

O2 will never call you to sell you a phone - if that is what has happened, it's an unscrupulous Trusted Partner, @Bilbo.