Update: After escalating things via the social media team, I got a call and someone else who still couldn't confirm if they've found the original phone call at the start of February.
She went through a scripted response about how unhappy people are to have been moved off the One Plan, the best plan they've ever done and with some people paying as little as £12 (really? Damn, wish I'd paid that!) etc.
She then went on to say that the plan I'd been offered was an error, and it was also a plan that should have had just 2GB tethering. I then interrupted and said that 2GB was always handset plans, but she then went on to say that they may have agreed £20 but it was a mistake and the best price was £28.
Bear in mind, I'd already been asked for £4 extra before for 12GB tethering. Now I'm asked for £8 more. And apparently NOBODY has ever had a discount as Three is not allowed to discount. I was given a one off deal, except I wasn't as they put me on a £30 rate anyway - and the wrong amount of minutes and tethering.
They literally say something different every time you speak to them, but to cut a long story short, I said I'd have to take the PAC as I was being lied to, and she did.
I then followed up my disgust with the social media team who replied that because I've asked for my PAC, the complaint was closed and considered sorted!
I am now requesting a copy of my account details, the recordings of the calls and anything else as surely they have to honour a deal made on the phone? While I expect they have a right to refuse to sell to anyone, they surely must have suitable grounds.
Of course they've made me ask to disconnect by not agreeing to paying £28. For 600 minutes!
They have refunded my line rental for the month and they advised me to cancel my direct debit, which I said I wouldn't do as I can just imagine them having an outstanding amount that leads to legal action.
A total bunch of incompetent idiots. I told them they'd put me on an old plan and they could fix it, but no, they've stuck to the line that I can't have the deal and it was a mistake..