Hello Katherine,
I would like to wish you a warm welcome to the TrustedHousesitters forum. Here you will find lots of experienced members that can offer helpful tips and advice. I hope that you connect with some of them and find it useful.
I am sorry to hear that you had a housesit where all of the pet care duties were not carried out as you had hoped. Did you communicate this to the sitters after the sit? It can be very helpful to reach out to the sitters and give some feedback and ask if they had any issues carrying out any tasks during the sit. Clear communication before, during and after is often the key to helping things go smoothly.
There are other forum topics which have discussed a similar issue and advise on how to leave a review and this might prove helpful to you.