I would have either asked for a refund ASAP (which sounds like in there books as slow as possible) or tell them i want a discount on the price of the tyres seeming as its falsely advertised and said next day delivery.
I hate it when companies do this, or i one that really tweeks me is they say X am of pounds to UK then once youve ordered a load of stuff they change there mind and now say oh that was only UK Mainland its another �X on top of that.