I've just bought a 250g packet of Red Leicester from ASDA.
On the back in small print is says:
TRY ME, LOVE ME
We'll refund and replace if you are not 100% happy
phone us on: 0845 300 1111
or visit our website: http://www.asda.com
I must say this is not the finest Red Leicester I have had, it's a bit too soft and tasteless.
It is hard to imagine that anyone would be 100% happy with it. So try them on their offer and get your MONEY BACK AND A REPLACEMENT. Even if you are 95% happy with it.
They might also have this offer on a lot more of their foods. So if you are not 100% happy with it phone them and get a replacement and your money back.
100% happy is quite a lot to live up to, so I would think that almost everything they have this offer is up for a refund and your money back.