How does that work? - glitch, charging me more :S

Ive added a showing as £10.00 then added the new Swoon Drive Me Balmy stimulating Orgasm Balm for just £3 when you buy anything at Lovehoney!

And its coming to a grand total of £15 - with the free postage option

Now I was never good at maths but surely that should be £13 -free postage