I'm sorry if your stay was not the best or as expected.
Dear......If the apartment was as dirty as you say, you should had call me only and I would have sent you the cleaning lady immediately. This apartment was rented to much more than 70 groups and nobody never complained. However I might understand that this could happens and as I am the manager I would have solved it straight away.
Also, please understand that with a slightly higher budget I would have served you with another apartment of mine, maybe more suitable for your requests.
Have a good day