I received a text message from T-Mobile over the weekend inviting me to look at new offers
here.
There are rewards like £10 free at weekends when you top up £10 between Monday - Friday, and text Stretch to 441;
other reward options for topping up;
the ongoing topup Friday offer;
Euro travel 'boosters' ( 19 minutes or 18 texts for £5 from many European countries );
International text boosters;
a 5 day unlimited pass for calls and texts to T-Mobile 'phones;
and unlimited browsing on your mobile for 50p per day ( £2-50 for 5 days ).
See:- http://www.t-mobile.co.uk/pay-as-you-go/top-up/