Mobile - how do we get a lower tarif in order to end contract with 3

Lovingitifitsabargain

I am trying to sort out my sons finances as he is in so much debt - anyway got to the mobile phone and he is paying 56.00 a month with 3 - he obviosuly uses up the minutes and texts he gets free as his bills are so high from him over using it - last one I paid was 243.00 (yes I paid) anyway checked it out and his 18 month contract ends in July s to cancel now would mean paying up 5 months line rental - I saw a part on here which recommends asking fo a lower tariff then keeping it for a month and then paying off the months left at the lower rate - but I noticed that under the heading sites not useful were 3 so my question is - has anyone had any dealing with 3 on this sort of thing or can anyone advise me on what to do for the best - thank you - oh and by the way I have the sim card and he hasn't used since xmas (the phones busted too ) thanks again