In the last few weeks I have received 2 £10 off a purchase above £20 vouchers from Joules, both vouchers have failed to work despite being well in date. I emailed them but didn't receive a reply until I had chased them up and by then, what a coincidence [hhmm], both the vouchers had run out.
They have now offered me 15% off a future purchase - not really comparable to their vouchers.
I used to find Joules a really good online shop, although I've read other comments saying their customer service is poor, now I feel really let down.