[Question] When online prices do not match the invoice

[Jacks in Betty's Bay]

Can someone please point me in the right direction? ... A supplier of mine encouraged me to use their new (third party run) shopping portal for beverages (I am a restaurant owner). I compared prices and made an online order only to find once the goods were delivered that the prices on the portal were wrong - the invoice that I signed was correct. The supplier will not honour the online portal prices... who can I take this to do you think?

[Dave A]

My first thought was the Advertising Standards Authority. However, I notice that they're currently in business rescue, so I'm not sure how effective they may be at the moment.

[Electrode]

My advice is to find a good lawyer.

[BusFact]

1) Are the amounts involved substantial?
2) Are there alternative suppliers?