Log on to your Tesco mobile account online and you can get a £20 voucher off an upgrade for your phone!
I've been with them for a year or two, but don't know how soon the offer's available, but it's worth a look!!
I logged on to register for Ping me a Pound and it gave me the option to request a £20 voucher off a new phone bought in-store, voucher arrived today and there's no MOV.
In fact, if the phone you choose is less than £20, you get the rest of the voucher as airtime.
Excellent offer for buying the kids a cheap phone!