I cancelled my order with dialaphone as their customer service was terrible and they couldn't tell me when my phone would arrive. I saw the £22 p/m contract online with Three but decided to go in store to see what they'd offer. I was initially told this offer but for £19, however they didn't have any in stock so they ordered it online for me. Online includes a discount of £2 (apparently) which took it down to £17 a month in store. If you go in store, ask for them to order it online for delivery to your home to get this deal.
This is EXACTLY the same as the Internet Texter 100 plan on their site but it's only £17 per month.