Purchased Boots Antihistamine tablets 30pk over the counter and they were on BOGOF offer, so 60 tablets for £2.99.
However, it ALSO applied a multisave offer to it of -£2.99 meaning that the Total came to £0.00.
I was buying 4 packets and the total came to £0.00!!!!
This will only work if you purchase other items so that they are "hidden" within your shopping....