Order Completion Rates


Recently I got two orders. One of 130$ dollars but another is 30$ dollars. I say sorry to the customer for 30$ dollar cancel the project. but my order completetion rate decreased too much Now it’s about 84% Now I complete the order 130$ and 50$ dollars but my order completetion rate still 84% How I can improve it?
If i will not do this more then 90% then my rate level will decreased any suggestion?