I have been under the annual maintenance plan for ...

I have been under the annual maintenance plan for the past 4 years and never had a problem. The past few services I discovered the tech who serviced my units installed the air filters upside down. I corrected it and didn't bother to bring it to their attention. The last maintenance performed the tech didn't even bother to replace the filters even though he noted it on the receipt that he did. I discovered this about 2 months after he supposedly replaced them. I found filters I installed about 5 months ago ( I replace them every 3 months) and they were practically disintegrated. I did bring this to their attention and was ready to cancel the contract (which I had just renewed shortly before the tech came out). They offered to "re-train" the tech and provide me with a free annual contract for the following renewal period. I also requested they not send that tech out to service my units in the future, which they agreed. We will see if they keep their promise.