It looks as if the Tesco Green Clubcard deal for recycling mobile phones is dropping in value. As of 31 August the link to deal http://www.tesco.com/greenclubcardpoints/
shows 500 points (100 for a broken phone), but the link https://secure.tesco.com/clubcard/clubcard/partners/?page=recycle
shows 300 points (50 for a broken phone.
Even worse, you are limited to 5 phones a year.
However, if you go to your local Tesco store, you may be able to get the old envelopes by asking customer services to give you some. I got 4 today.
The terms and conditions on the old 500 point envelopes do not show any limit to the number of phones, and there is no expiry date on the offer. Therefore it is more likely that Tesco will honour the terms on the envelope from the stores.