Credit to Pavel76 from another post but feel this offer should be shared.
Deal for anyone within the final 30 days of their contact (or I beleive anyone on a rolling contract and a minimum of 3 months in). Only available via the link. If you call retentions they won't beleive this deal exists.http://www.three.co.uk/simplans6
£19 per month for unlimited mins, texts and data. feel at home and 30gb of tethering. 12m contact
I understand this will only be suitable for a small amount of people like myself but as many others have found Three retentions had turned rubbish and they only seem to offer deals available to new customers. at least that's what i found despite being a customer for many years!
I followed this link and within 4 days got the text confirming my tariff is being updated on my next bill cycle. others too confirmed it worked despite not being on the "your current plan" the link suggests you're meant to be on.
Once you sign up, log into your account online and hit the upgrades tab to see if you have been upgraded to this deal. You can see my screenshots on comment #96 and #98 (page 3 on a PC)
New update - once you have seen the updated tarriff on your account, you can call customer services on 333 opt 4,4,4,4 and ask for your tarriff to be activated early for a £3 charge. I called on the 21st and by lunch time on the 22nd my new tarriff was active.
hope this helps anyone who missed the link in the £20 for 30gb data deal comments.