Holiday cottage refund?

We rented a cottage which was dirty with lots of broken items and out of date food left in the kitchen. We had already had the owner's agent in to do the kitchen cleaning (which they did very badly!), we didn't feel that they could do any better on clearing other things.. tissues under the bed, unemptied bin, minging bathroom etc.

We decided to leave the next day and rented another property for the week. We told the agent that we had left, and why. As we were only there for a week we wanted a proper holiday and not to have any hassle, so we told the agent that we would take the matter up with the property owner on our return.

We emailed the owner a list of the complaints, together with the photographic evidence. They have responded, refusing any compensation, and accusing us of planting dirty items around the house!

What to do? Last resort is always Trip Advisor of course, but it would be good to get some recompense.

We paid the owner directly. The agent is only someone from the village, not a proper agent (I didn't know what else to call them). Of course the owner will believe their side of the story, I guess.

I know we should probably have gone round with the agent and pointed out all the problems, but as I've said -we were there for a holiday and desperately needed some peace, not arguments about dirty tissues under the bed.