Truworths not honoring online sale

I have ordered a shoe and a shirt online on a sale. I received an sms 3 days later stating that the shoe is not available. I logged on this morning and found that the shoe is still available to order on the website but at the normal cost.

This is absolutely ridiculous as I paid delivery fee and all just to get the shirt which is not actually what I wanted , I only took the shirt ad I felt the price was low but the shoe is the main thing I wanted but truworths won't honour a deal that they had on their website.