False advertising or uninformed staff?

The catalogue has a hair special and your wording state: 'Shampoo,Conditioner or Treatments. 350ml or 355ml

I went to my nearest clicks and got a Conditioner and Treatment, got to the till and it was not accepted for the advertised deal and was told it was due to 'ml on the treatment does not match the ml on the conditioner (They apparently need to be the exact same ml) .

I went back to the shelf to change the treatment to the same ml, however dove DOES NOT have and have never released a treatment above 200ml. I checked the Clicks website and surprise, clicks doesn't even sell any other Dove treatments than the 200ml. - Also couldn't change the conditioner as the 200ml conditioner doesn't apply to the special.

So please explain why specials are either falsely advertised to say or treatments when the Clicks Company only sells one specific Dove 200ml treatment across all shops or if the staff is uninformed that the ml on the pamphlet is for the Conditioner/Shampoo which comes in different sizes. Not a happy client.