Hi can anyone help?

We bought 6 months worth of milbemax worming tablets in August from our vets, and last night i noticed that all the remaining tablets are out of date!!! (aug 08!!)

So that means the kittens have had two doses of tablets that had expired back in August, i am going into the vets on saturday morning to exchange the remaining tablets and to have a word with them but does anyone know if this will have harmed the babies or will they have not been wormed as such??

Im so cross!! i know i should have checked before giving them the tablets but i suppose i just trusted my vet!