JMJ,
Not knowing what the other cleaner has done is a problem - the stain may now be set. Make the lad aware of the implications and possible out come before proceeding.
The best approach under the circumstances is to first give the stain a fresh-water rinse to remove any residue from previouse attempts. In similar circumstances I have done this and had the stain come strait out !
Assuming you are not this lucky, treat with Chemspec Juice & Dye spotter, agitate gently, allow 5 minute dwell then blot. If you get colour transfer but stain is still evident, repeat proceedure.
Rinse thoroughly.
If required, treat with Chemspec Spray'N'Go.
If you do not have Chemspec J&D you could substitute Prochem B175.
I would not simply use Red RX since, if the stain has been treated with high pH products it is unlikely to work and the last thing you wish to do is to heat-set the stain if this has not already occurred.
John.