Re: 11 y/o not potty trained HELP!!
My preference would be for a behavioral therapist who could help you set up & run a training program at home.
An 11 yo (& younger) is fully capable of scrubbing out stains, cleaning self up, etc. This should be part of the consequence for the episodes.
But any behavioral training program worth it's weight will focus on rewarding appropriate voiding, i.e. in the toilet.
At 11 you will soon be dealing with puberty issues & need for privacy, etc. which will tend to complicate resolution of the issue.
Since your son is 11 & middle school is 2 yrs. away, might there be a learning deficit contributing to the problem?
If you think his behavior has a passive-aggressive streak to it, a psychologist may be able to help you all work it through.