Waitrose money off vouchers which you can't print.

Waitrose send me offers of £10 off sixty pound shops. However they have to be printed and although I followed all instructions no joy. Very frustrating as if they arrive by post there is little or no time to use them. I buy shopping on line but still cannot receive the necessary codes. Why they can't e mail the codes instead of using a system that does not work it is difficult to understand. They are quoting my Waitrose card no so they know who they are sending them to.