I'm going to have to agree with everything stated. I've recently had similar experiences with commissioners on here, and needless to say I am not pleased. I should not have to badger you for progress pics, or even updates in general. I should not be ignored 9 times out of 10 that I send you an IM.
Three friends of mine are currently going through the same issue with a commissioner that came extremely highly recommended. Bare bones communication, no progress pictures, and there are about three weeks left until the convention and they still don't have their costumes. It's really shameful.
If you can't commit to the service you promised to provide, for ANY reason, you need to grow a pair, refund the person, and suck it up instead of stringing them along and hoping you can get it done in time.
Anime Expo & Otakon
★Shizuma (Strawberry Panic!) - 50% complete
★Saber (Fate/Zero) - 45% complete
★Rachel Alucard (Blazblue) - 100% complete